The Science Hub - SARASWATI HOUSE Material/978-93-5199-717... · TEACHER’S MANUAL Class 6 Gautam...

(An imprint of New Saraswati House (India) Pvt. Ltd.)New Delhi-110002 (INDIA)

TEACHER’S MANUAL

Class 6

Gautam BindalMSc

Science HubThe

(An imprint of New Saraswati House (India) Pvt. Ltd.)

R

First published 2016

ISBN: 978-93-5199-717-7

Preface Th e purpose of � e Science Hub series (1 to 8) teacher’s resource pack is to empower teachers to make classroom teaching a holistic experience. It will enable teachers to explain the chapters in the most eff ective way, which will not only impart knowledge, but also ignite interest in the minds of young learners towards the subject. A wide array of resources complement these manuals, which makes learning an interesting process instead of a routine chore.

Teacher’s ManualTeacher’s Manual resources have been carefully prepared with an aim to make the process of teaching and learning interesting and intriguing for the teachers and learners alike. It comprises detailed lesson plans and answers to the coursebook along with solved worksheets and model test papers. Th ese have been prepared keeping in mind the explanation of the concepts and the level appropriateness of the topics. Easily available teaching aids are used to make teaching and learning an interactive and lucid process.Th e lesson plans give a topic-wise explanation of each chapter. Its components are:

• Warm up section guides the teacher to start the topic in an interesting way.

• Speci� c learning objectives give the list of measurable aims of each chapter, which should be achieved aft er teaching the chapter.

• Concept explanation gives a detailed method of explaining the important concepts of the chapter using various teaching aids.

• Reinforce section allows the teacher to check the progress of the concepts learned by the students with the help of textual questions and worksheets and allows them to revisit and revise the concepts, if required.

• Explore section helps the learners to do various activities , oft en taking them beyond their classroom learning.

Teacher’s CDTeacher’s CD comprises animations, activities, fl ip book, detailed lesson plans and answers to the coursebook along with solved worksheets and model test papers.

Web SupportTh e web support consists of worksheets, model test papers, and answers to worksheets and model test papers. Th ese would help teachers in assessing students on the concepts taught in the class.

Contents S.No. Chapters Pages

1. Sources of Food 5

2. Components of Food 10

3. Fibre to Fabric 17

4. Grouping Materials 24

5. Separation of Substances 31

6. Changes Around Us 38

7. Living and Non-living Th ings 44

8. Plants and their Parts 51

9. Body Movements 58

10. Habitat and Adaptation 64

• Model Test Paper 1 75

11. Motion and Measurement 78

12. Light, Shadow and Refl ection 85

13. Fun with Magnets 91

14. Electricity and Circuits 98

15. Water 105

16. Air 112

17. Garbage In, Garbage Out 118


Contents S.No. Chapters Pages S.No. Chapters Pages

1. Sources of Food 5

2. Components of Food 10

3. Fibre to Fabric 17

4. Grouping Materials 24

5. Separation of Substances 31

6. Changes Around Us 38

7. Living and Non-living Th ings 44

8. Plants and their Parts 51

9. Body Movements 58

10. Habitat and Adaptation 64


11. Motion and Measurement 78

12. Light, Shadow and Refl ection 85

13. Fun with Magnets 91

14. Electricity and Circuits 98

15. Water 105

16. Air 112

17. Garbage In, Garbage Out 118


5

Chapter 1Sources of Food

Specific Learning Objectives Aft er the completion of the chapter, students will be able to: • Tellthedifferentsourcesoffood • Enumeratetheimportanceoffoodinourbody. • Understandthedifferencebetweenherbivores,carnivoresandomnivores. • Listexamplesofdifferentediblepartsofplants. • Knowthemethodofobtainingsprouts. • Learnaboutfoodchains.

Warm UpTomaketheclassinteractive,startbyaskingthemquestionslike-Whatarethedifferentpartsofaplant?Whydoweneedfood?Whatarethedifferenttypesoffoodthatareeatenindifferentpartsofthecountry?AskthestudentstothinkandanswerthesequestionsandthendotheWarm-upsection.

Concept Explanation • Sources of food:Explaintothestudentsthatfoodcanbeobtainedeitherfromplantsource

oranimalsource.Listavarietyofexamplestojustifythis.Askstudentstolistexamplesfromtheirsidealso.Th eclassshouldhaveatwo-wayinteraction.

• Food habits:Studentsshouldalreadyknowaboutherbivores,carnivoresandomnivoresastheymusthavelearntaboutthemintheirpreviousclasses.Youcanstartthetopicbygivingalistofanimalsandaskthestudentstoclassifythemonthebasisofthetypeoffoodconsumedbythegivenanimals.Youcanthencoverthefeaturesofthedifferentcategoriesonebyone.

• Food chain:Explaintostudentsthathoworganismsdependoneachotherfortheir foodrequirements.Th eyshouldbetoldtheimportanceoffoodchainintheenvironmentandhowanimalsdependonplantsdirectlyandindirectlyfortheirfoodrequirements.

Reinforce • Studentsshouldbeaskedtodothein-textexercises,activitiesandexercisesgivenattheend

ofthechapterontheirown.Th eteachershouldthendiscusstheseintheclass.HelpstudentstoacquirevaluesandthinkingabilitiesbydoingtheLifeSkillsandHOTSsectiongiveninthechapter.

Explore • Students can further extend their knowledge by completing the project given on

page15.Debategivenonpage15undertheLet’sSpeaksectioncanbeusedasaformativeassessmentinterdisciplinaryactivity(ScienceandEnglish).

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Worksheet 1 1. Match the given food items to the part of the plant to which they belong.

ROOT

STEM

LEAVES

FRUIT

2. Tick () the food items that are obtained from animals. (a) Honey (b) Eggs (c) Mustardoil (d)Milk (e) Grains (f) Cheese

3. Identify the types of animals on the basis of the given characteristics? (a) Broadandbluntteeth. ______________ (b) Havedifferenttypesofteeth. ______________ (c) Havesharpandpointedbeaks. ______________ (d) Canbringbackthechewedfoodtoagainchewitproperly. ______________ (e) Havesharpclaws. ______________ (f) Caneatbothplantsandanimals. ______________

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Worksheet 2 1. Give two examples of each of the following.

(a) Scavengers (b) Carnivores

(i) (i)

(ii) (ii)

(c) Decomposers (d) EdibleLeaves

(i) (i)

(ii) (ii)

(e) Herbivores (f) EdibleFlowers

(i) (i)

(ii) (ii)

2. Complete the following food chains. (a) GrasshopperLizard (b) PlantsDeer

3. Fill in the blanks.

(a) Animalfoodisarichsourceof and .

(b) Animals that canbringback thehalf chewed and swallowed food to chew itproperlyarecalled .

(c) A sequenceofoneorganismconsumingother inaparticular environment iscalled a .

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Answers to Coursebook

A. 1. (a) (ii) (b) (iv) (c) (iii) (d) (iii) (e) (iii) 2. (a) False (b) True (c) False (d) False (e) True

B. 1. Green plants are called producers because they prepare their own food by the process ofphotosynthesis.

2. Th reeflowerswhichareeatenasfoodarecauliflower,broccoliandbanana. 3. Animalproductsthatweeatasfoodaremilkanddairyproducts,animalflesh,eggsandhoney. 4. Examplesofdecomposersaremicrobeslikebacteriaandfungi. 5. Productsmadebyusingmilkarecalleddairyproducts.Forexample:cheese,curd,butterandghee. 6. Weneedfoodas itprovidesenergytoperformvariousactivities.Ithelps ingrowth,repair,and

developmentofourbodyanditprotectsusfromvariousdiseases.

C. 1.Plant Parts Examples

Stem Potatoandginger

Leaf Cabbageandspinach

Root Carrotandturnip

2. (a)Nutrients: Componentsof food thatprovideenergyandhelporganisms toperformvariousactivitiesarecallednutrients.Examplesofnutrientsareproteins,carbohydrates,fats,vitamins,etc.Th eyhelp ingrowthand repairofourbody.Th eyalsohelpus tofight against variousdiseases.

(b)Omnivores:Animalsthateatboththefleshofotheranimalsandplantsarecalledomnivores.Forexample:dog,crow,bear,etc.

(c)Consumers:Organismsthatdependonplantsfortheirfoodastheycannotmaketheirownfoodarecalledconsumers.Forexample:animals,birds,humanbeings,etc.

(d)Food chain:Th echainofeatingandbeingeateniscalledfoodchain.Forexample:rabbiteatscarrots;asnakeeatstherabbitandaneagleeatsthesnake.

3. Typesofanimalsbasedontheirfoodhabits: (i) Herbivores (ii) Carnivores (iii) Omnivores (iv) Scavengers (v) Parasites (vi) Decomposers

Herbivores: Animals that eat plants and plant products only are called herbivores. Examples ofherbivoresaredeer,rabbit,goats,etc.

Scavengers:Animalsthateatthedeadremainsofotheranimalswhichareleftbehindaftercarnivoreshavefedonthemarecalledscavengers.Forexamples:vulturesandhyenas.

4. Wegethoneyfromhoneybees. Honeyhascarbohydrateslikeglucose,fructoseandsugars,vitaminsandminerals.

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5.Teeth of Herbivores Teeth of Carnivores

Th ey have broad and blunt teeth,which are suitable forpullingplantsandchewingthem.

Th ey have sharp and pointed teeth which aresuitablefortearingthefleshofotheranimals.

D. Agrasshoppereatsgrass;arateatsthegrasshopper;asnakeeatstheratandaneagleeatsthesnake.Whentheeagleisdead,itsremainsarebrokendownintonutrientsbydecomposerssuchasmushrooms(fungi).Infact,mushroomsbreakdownthedeadremainsofsnake,rat,grasshopperandplantsandturnthemintonutrientswhicharethenreleasedintothesoil.Th isrepresentsafoodchain.Inthischain,grassistheproducerwhileothersareconsumers.

E. 1. Carnivoressuchaslions,eagleshuntdownotheranimalsandeattheirfleshwhereasscavengerssuchashyenaseatthedeadremainsofanimalswhichareleftbehindafterthecarnivoreshavefedonthem.Scavengershelpincleaningtheenvironment.

2. Greenplantsarecalledproducersastheymaketheirownfoodwiththehelpoftheprocesscalledphotosynthesis.Herbivoreseatplantsandtheirpartsandcarnivoreseatherbivores.Ifplantswerenot there, thewhole food chainwouldhave gotdisrupted. So, one can say that all animals aredependentdirectlyorindirectlyonplantsfortheirfood.

3. Namesofplants,ofwhichbudsareeatenasfoodarecauliflower,broccoli,cloves,etc.

Answers to Worksheets

Worksheet 1

1. Root-Turnip,Stem-Potato,Leaves-Spinach,Fruit-Brinjal

2. (a),(b),(d)and(f)

3. (a)Herbivores (b) Omnivores

(c) Carnivoresoromnivores (d) Ruminants

(e) Carnivores (f) Omnivores

Worksheet 2

1. (a) Hyenasandvultures (b) Lionsandowls

(c) Bacteriaandfungi (d) Spinachandbasil

(e) Cowsandbutterfly (f) Bananaandcauliflower

2. (a) Grass,Snake (b) Lion

3. (a)Proteinsandfats (b) Ruminants

(c) Foodchain

10

Chapter 2Components of Food

Specific Learning Objectives Aft er the completion of the chapter, students will be able to: • Listthedifferentnutrientsrequiredbythebody. • Understandtheimportanceofdifferentnutrientstomaintainahealthylife. • Understandtheimportanceofabalanceddiet. • Tellsomeofthenutritionaldeficiencydiseasesalongwiththeirsymptoms. • Performsomesimpleexperimentstotestthepresenceofaparticularnutrientinthegiven

fooditem.

Materials RequiredTeaching Aids: Th efollowingteachingaidscanbeusedtoexplaintheproposedchapter:Materialsrequired to test thepresenceof starch, sugar, fatsandproteins in thegiven food item,picturesshowingdifferentdeficiencydiseases.

Warm UpClasscanbemadeinteractivebydoingwiththeexerciseoftheWarm-upsection.Studentswillbeaskedtoselectthehealthierdietforthemamongthetwolistedintheexercise.Studentsarethenaskedtheimportanceofahealthydietandlistsomeotherfooditemsapartfromtheonesgiveninthepicturethatmightbeaddedtothehealthydietcolumn.

Concept Explanation • Nutrients:Explaintothestudentsthemeaningofthetermnutrientsandlistthevarious

nutrientsrequiredbyourbody.Explaintothemtheimportanceofthefivenutrientsalongwiththeroleofwaterandroughage.

Classcanbemademoreinterestingbyperformingtheexperimentsfornutrienttestaslistedinthechapteronpages17-20.

• Balanced Diet:Listsomefooditemsthatcontainall thenutrientsbutnot inabalancedamount,forexample,burger,thatisarichsourceoffats(friedpart),carbohydrates(potatoandbread),vitaminsandminerals(vegetables),proteins(cheese,meat).Askthestudentstocommentontheconsumptionofburgerasitcontainsallthenutrients.Aftertakingstudent'sviewpoint,introducetheconceptofbalanceddiettothem.

• Defi ciency diseases: Explain to the students the need to take all the nutrients and thediseasesthatcanoccurduetolackofintakeofanyparticularnutrientforalongtime.Also,tellthemaboutthesymptomsofthesediseases.Afterdiscussingallthediseasesgiveninthechapteryoucanshowstudentssomepicturesdepictingtheeffectofthesediseasesandaskthestudentstoidentifythediseaseanditsconcernednutrientsandsymptoms.

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Reinforce • Ask the students to complete the activities given in the chapter on page 20 and the in-

textexercisegivenas ‘Breather’onpage24.Helpstudents todevelopvaluesandskillsbyconsideringthetaskgivenunder‘Values’,‘Innovator’sCorner’and‘LifeSkills’sectionsofthechapter.Exercisesgivenintheendwillhelpintherecapitulationofthechapter.

Explore • Askthestudentstocompletetheprojectgivenattheendofthechapter.

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Worksheet 1 1. Fill in the blanks to complete the test for proteins. Takeasmallquantityoffoodsampletobetestedandconvertitinto

form.Putitintoatesttubeandaddafewdropsof toit.Nowadd two drops of solution and solution to it.Shakethetesttubewell.A indicates the presence of proteins inthegivenfooditem.

2. Match the following food items to the type of nutrient they are rich in. FOOD ITEM NUTRIENT

(a) Carbohydrates

(b) Vitamins

(c) Proteins

(d) Fats

3. Write any two functions of water in human body.

4. Write the names of any two diseases caused due to the lack of protein and vitamins.

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Worksheet 2 1. Select the nutrient being referred to in the following sentences. (a) Iprovideenergytothebody. (b) Icanbesynthesisedbytheskininthepresenceofsunlight. (c) Imaintainwaterbalanceinthebody. (d) Iamrichlyfoundiniodisedsaltandseafood. (e) Iamrequiredbythebodyinsmallamounts. (f) Iamobtainedfrombothplantandanimalsources. (g) Ihelpintherepairofoldandwornoutcells. (h) Ihelpinbloodclotting. (i) Ihealcutsandwoundsandkeepthegumshealthy. (j) Ihelpinbodygrowth.

2. Fill up the blanks to complete the test for sugars in a food item. (a) Crushasmallamountoffooditemanddissolveitin . (b) Takethefooditeminthetesttubeandshakeitwell. (c) Addafewdropsof in the test tube and heat it on a

burnerforaminute. (d) Differentcolouredprecipitatesconfirmthepresenceofsugars: (i) Greencolourrefersto . (ii) Yellowcolourrefersto . (iii) Orangeorbrickredcolourrefersto .

3. Write any two functions of roughage in human body.

4. What occurs due to defi ciency of water? How can we cure it?

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A. 1. (a) balanced (b) carbohydrates,proteins,fats,vitamins,minerals,roughage (c) deficiencydiseases (d) Bcomplex,C (e) obesity (f) Obesity (g)Milk,eggs

2. (a) False (b) True (c) True (d) False (e) True 3.

Mineral Function

Calcium Itkeepsbonesandteethhealthy.Iron Ithelpsintheformationofhaemoglobinpresentinredblood

cellswhichcarriesoxygeninthebody.SodiumandPotassium Th eymaintainthebalanceofwaterinthebody.

4.Constipation Dehydration

It is a condition in which difficulty isfacedbyapersoninemptyingbowels.

Excesslossofwaterfromthebodyleadstoaconditioncalleddehydration.

5.

Sources Greenleafyvegetables,kiwifruit,parsleyandsoyabeanoilImportance Ithelpsinclottingofblood.Deficiencydisease Itreducesbloodclottingwhichresultsinexcessivebleedingfromthe

wounds.

B. 1. ORSstandsforOralRehydrationSolution.Itismadebymixingsaltandsugarinwater. 2. Roughagedoesnotcontainanynutrientsbutitkeepsourdigestivesystemhealthyasithelpsthe

foodtopasseasilythroughthedigestivesystemandthushelpsindigestion. 4. Testforthepresenceofproteinsinthefooditem Materialrequired:Foodsample,water,coppersulphatesolution,causticsodasolution,droppers

andtesttubes. Procedure: Takeasmallquantityoffoodsampleandcrushitintopowderedform.Putthecrushed

powderinthetesttubeandaddafewdropsofwatertoit.Nowadd2dropsofcoppersulphatesolutionandcausticsodasolutiontoit.Shakethetesttubewell.Formationofvioletcolourindicatesthepresenceofproteinsinthetestedfoodsample.

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C. 1.Nutrients ImportanceVitaminC Ithelpsinquickhealingofcutsandwoundsandalsokeepsthegumshealthy.Iron It helps in the formation of haemoglobin present in red blood cells which

carriesoxygeninthebody.Magnesium Itregulatesthefunctioningofnervesandmuscles.Iodine Itpromotesthephysicalandmentaldevelopmentinchildren.VitaminD Ithelpsinabsorbingcalciumandphosphorusforstrongbonesandteeth.

2. Deficiency diseases: Diseasesthatoccurinourbodyduetothelackofnutrientsforalongperiodoftimearecalleddeficiencydiseases.

Deficiency disease Nutrient SymptomsMarasmus Proteins Dry skin, fatigue, rapid weight loss, weak legs,

mentalretardationandpoormuscledevelopmentRickets VitaminD BonesbecomesoftandbendeasilyGoitre Iodine Swollenneckandmentaldisabilityinchildren

3. Balanced diet: Adietwhichcontainsallthenutrientsintheproperamountiscalledbalanceddiet. Balanceddietchartforaweek

Day Breakfast Lunch Dinner

1 Medium bowlof milk withwholegraincereal

1 bowl dal + 1 small bowlvegetable+2-3chapatis+1smallbowl salad

1 bowl dal + 1 small bowlvegetable+2chapatis+1smallbowlsalad+1mediumfruit

2 Vegetablesandwichandglassofmilk

1 bowl dal + 1 small bowlvegetable+1bowlcookedrice+1smallbowlsalad

1 bowl dal + 1 small bowlvegetable + 1 bowl cookedrice + 1 small bowl salad+ 1medium fruit

3 Omelette andorangejuice

1 bowl dal + 1 small bowlvegetable+2-3chapatis +1smallbowl salad


4 Medium bowlof milk withwholegraincereal

1 bowl dal + 1 small bowlvegetable+1bowlcookedrice+1small bowl salad

1 bowl dal + 1 small bowlvegetable+1bowlcookedrice+1smallbowlsalad+1mediumfruit

5 Fruit salad and glassofmilk



6 Idli with chutneyand sambhar

1 bowl dal + 1 small bowlvegetable+1bowlcookedrice+1smallbowlsalad

1 bowl vegetable with gravy +1 bowl cooked rice + 1 smallbowlsalad+1mediumfruit

7 Upma with mixedvegetables



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D. Inthepicture,contentsofOralRehydrationSolution(ORS)areshown.ORSisgiventothepatientintheconditionofdehydration.Itscontentscontainssodiumandpotassiumsaltswhichhelpinmaintainingthebalanceofwaterinourbody.Italsocontainsglucosewhichisacarbohydrateanditsmainfunctionistoprovideenergytothebody.

E. 1. Itisnecessarytoincluderawvegetablesandfruitsinourdietbecause (a) theyhelpthefoodtopasseasilythroughthedigestivesystemandthushelpindigestion. (b) theyretainwaterandmaintainhealthycholesterolandbloodsugarlevelinthebody. (c) theypreventconstipation. (d) theyalsohelpinkeepingusfull. 2. (a) Citrusfruitskeepthegumshealthy. (b) Citrus fruits contain vitamin C. Other sources of vitamin C are amla, papaya, broccoli,

berries,greenleafyvegetables,tomatoesandcapsicum.


Worksheet 1

1. Powdered,water,coppersulphate,Causticsoda,Violetcolour

2. (a) Potato (b) Fruits

(c) Soyabean (d) Butter

3. Functions of water:Itabsorbsnutrientsfromthefood.Ithelpstomaintainconstantbodytemperature.

4. Diseasescausedduetodeficiencyofproteins-Kwashiorkorandmarasmus

Diseasescausedduetodeficiencyofvitamins-Nightblindnessandanaemia

Worksheet 2

1. (a)Fats (b) VitaminD (c) Sodiumandpotassium

(d) Iodine (e) Tracemineral (f) Fat/Protein

(g)Protein (h) VitaminK (i) VitaminC

(j) Protein

2. (a) water (c) Benedict’sreagent

(d) (i)Lowsugarcontent,(ii)Mediumsugarcontent,(iii)Highsugarcontent

3. Ithelpsthefoodtopassthroughthedigestivesystemanditalsohelpstokeepusfeelingfull.

4. Dehydrationoccursduetodeficiencyofwater.Oralrehydrationsolution(ORS)isgiventothepatient

whoissufferingfromdehydration.

17

Chapter 3Fibre to Fabric

Specific Learning Objectives Aft er the completion of the chapter, students will be able to: • Listtheconditionsrequiredforthegrowthofcottonandjuteplants. • Tellaboutdifferenttypesoffibresknownalongwiththeirsources. • Understandtheprocessofobtainingfabricfromfibres. • Distinguishbetweenthetwotypesoffibres,i.e.,naturalandsynthetic. • Explaindifferenttermslikeginning,weaving,knittingandspinning.

Materials RequiredTeaching Aids:Differentfabricslikecotton,silk,jute,silkcotton,wool,coirandmaterialtoperformburningtestoffabrics.

Warm UpYoucanstartthetopicwiththeWarm-upsectiongivenonpage30ofthebook.Performingactivity1ofpage31canbeagoodwaytoproceedfurther.Forthis,youcanaskthestudentsadaybeforetobringsomesamplesoffabricsfromtheirhome.

Concept Explanation • Classifi cation of fi bres:Explaintothestudentsthatfibrescanbeobtainedfromtwodifferent

sources,onebeingplantandtheothertheanimalsource. • Plant fi bres:Cottonandjutecanbetakenasexamplestoexplainplantfibres.Askstudents

toperformactivitygivenonpage33toobtaincottonyarnfromcottonwool.Th estepsintheprocessingofcottoncanbeexplainedbyshowingthempicturesandifpossibleavideocanbeusedforthepurpose.Samecanbefollowedtoshowjutecultivation.Attheendofthetopic,studentscanbeaskedtocompletethein-textquestionsgivenas‘Breather’inthechapter.

• Animal Fibres:Explaintothestudentsthatfibrescanbeobtainedfromanimalsourcesalso.Woolandsilkcanbeusedasexampleshere.Studentscanbeaskedtofindoutaboutdifferentwoolyieldinganimalsfromaroundtheworldapartfromthoselistedinthechapter.

• Synthetic fi bres:Introducethetermartificialorsyntheticfibrestothestudents.Th eburningtestcanbeperformedwiththesyntheticfibresalsoandcanbeshowntotheclass.Askthestudentstoidentifythedifferenceintheburningpatternsofthetwotypesoffibres.

Reinforce • Arecapitulationofthechaptercanbedonebycompletingtheexercisegivenattheendofthe

chapter.QuestionsgivenunderHOTSandpicture-basedactivitycanbeusedtomaketheclassinterestinganddevelopthinkingskillsinthestudents.Makethestudentsunderstand

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the importanceof animalsandplants inobtainingfibres.Thiswilldevelopvaluesamongthem.Teacher’stipgivenonpage35canbeusedinaquestionformtomakethestudentsthinkaboutthereasonbehindit.

Explore • Theactivitiesgivenin‘Innovator’sCorner’and‘Project’canbeusedtofurtherextendthe

learningprocessinthestudents.Studentscanbeaskedtofindoutmoreonthe‘Historyofclothing’andthiscanbeusedasaformativeassessmentinterdisciplinaryproject(Scienceandsocialscience).

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Worksheet 1 1. Give two examples for each of the following.

(a) Plantfibres (b) Animalfibres

(i) (i)

(ii) (ii)

(c) Syntheticfibres (d) Wool-yieldinganimals

(i) (i)

(ii) (ii)

2. Arrange the following in proper order as they are followed in obtaining cotton fabric.

(a) Ginning

(b) Growingcottonplant

(c) Weaving

(d)Collectingcottonbolls

(e) Spinning

3. Identify the fi bre from the following statements.

(a) Iburnwithoutmeltingandgivethesmellofaburningpaper.

(b) Imeltonburning.

(c) Iammadefromthestemoftheflaxplant.

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Worksheet 2

1. Match the instrument with the process in which it is used.

(a) Spinning Looms

(b)Weaving Needles

(c) Knitting Takli and Charkha

2. Identify the fi bre from the following statements.

(a) Iammanufacturedusingchemicalsobtainedfrom petroleumproducts.

(b) Iamobtainedfromthecocoonofaworm.

(c) Iamobtainedfromthefleeceofcertainanimals.

(d) Iamawhitecolouredfibreobtainedfromafruit.

(e) Iamobtainedfromtheoutershellofcoconut.

(f) Iamobtainedfromthestemofaplant.

(g) Iamusedinthermalandsoundinsulation.

3. List the states of India in which the following fi bres are cultivated.

(a) Cotton

(b) Jute

(c) Silk

4. Write the conditions required for the cultivation of cotton and jute.

21


A. 1. (a)Sheepandyak (b)Woolandsilk (c) Rayonandnylon (d) Cottonandjute (e) Handspindleandspinningwheel (f) Knittingandweaving 2. (a) China (b) fabric (c) Barkoftrees,animalskin (d) ginning (e) juteB. 1.

Weaving Knitting

Inthismethod,twodistinctsetsofyarnsareinterlacedatrightanglestoformafabric.

Inthismethod,onlyasingleyarnisusedtomakeafabric.

2. Conditionsnecessaryforcultivationofcottonare: (a) Hightemperaturebetween21oCand30oC (b) Annualrainfallof50-100cm (c) Blacksoiloralluvialsoil

3. Jute ismajorly cultivated in SunderbansDelta as jute crop requires hot andhumid climate forgrowth.Lightsandyorclayeyloamarebestsuitedsoilsforgrowingjute.

4. Earlymenandwomendidnotwearclothes.DuringtheStoneAge,theyusedtocovertheirbodieswiththebarkoftrees,bigsizedleavesandanimalskinorfur.Th en6000yearsago,peoplestartedusingwool as fabric.Cottoncame intouse after the earlyman learnt about agriculture.Earlierpeopleusedtowearunstitchedclothes.Eventoday,peoplewearunstitchedclothessuchasdhoti, lungi and saree.

5. Jute stemhas thickbarkandcontainsfibres inside it. Jutefibresarenaturallyglued togetherbystickysubstance.Th isstickysubstanceisremovedbyaprocesscalledrettinginwhichjutestalksarecuttothegroundandtiedintobundles.Th esearethensoakedinwaterforabout20days.Afterretting,thefibresareseparatedfromthestem,washed,driedandtiedintobundles.Inthisway,jutefibresareseparatedfromjutestem.

6. Yarns aremade up of fibres. Processes bywhich yarns are turned into fabric are weaving andknitting.

C. 1. (a) Spinning:Th eprocessofmakingthreadoryarnsfromcottonfibreiscalledspinning.Itisdonewiththehelpofahandspindleoraspinningwheel.

(b) Retting:Th eprocessofseparatingjutefibresfromjuteplantsbyrottingofstemsofjuteplantsinwatertoremovestickysubstanceiscalledretting.

(c) Weaving:Th emethodinwhichtwodistinctsetsofyarnsareinterlacedatrightanglestoformafabriciscalledweaving.

2. Twoprocessesofmakingfabricfromyarnsareweavingandknitting.

Weavingistheoldestmethodofusingyarntomakefabricinwhichthreadsarewovenintoclothes

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on a loom.The looms are either hand operated called handloom or machine operated calledpowerloom.Thepatterninwhichtwodistinctsetsofyarnsareinterlacedatrightanglestoformafabriciscalledaweave.

Secondprocessofmakingfabricfromyarnsisknittinginwhichasingleyarnisusedtomakeafabric.Thiscanbedoneeitherusingknittingneedlesormachines.Aseriesofinterlocksorloopsaremadeintheyarntoformafabric.Theconsecutiverowsofloopsinaknittedfabriciscalledstitches.

3. Silkisobtainedfromthecocoonofthesilkwormswhicharefedontheleavesofthemulberryplant.

4. Classificationoffibres:

5.Fibre Property

Cotton AbsorbswaterquicklyFlax StrongfibreanddurableSilk-cotton FluffyandwaterrepellentJute HightensilestrengthHemp HightensilestrengthCoir Waterproofandresistanttodamage

6.

Other plant fibres ImportanceCoir Coir fibres arewaterproof and resistant to damage.They are used to

makedoormats,brushes,coirropes,sacks,etc.Silk-cotton Itsfibresarefluffyandwaterrepellentanditisusedinfillingmattresses

andlifejackets.Itisalsousedinthermalandsoundinsulation.Hemp Ithashightensilestrength,soitisusedinmakingropes,carpets,nets

andclothes.Flax Itsfibresarestronganddurableanditisusedinmakingropesandhigh

qualitypaper.

D. Sequenceofobtainingfabricfromplant

(c) Cultivationofcottonplant

(a) Ginning

(d) Spinningofcotton

(b) Weavingofcottonyarnintofabric

E. 1. Naturalfibressuchascottonabsorbwaterquicklywhilesyntheticfibressuchasnylonarewaterresistant.So,umbrellasandraincoatsaremadefromsyntheticfibres.

2. Silkisadelicatefabricwhichgetswrinkleseasilyandispronetodamagebyinsectsandonbleachingwhereassyntheticfibresarestrong,wrinklefree,insectresistantandeasytodye.

3. Indiahasthelargestamountoflandforcottoncultivationyetitisthesecondlargestproducerofcotton.Thisisprobablybecauseofvaryingconditionsoftemperatureandrainfallwhichdonotremainthesamethroughouttheyear.MoreoverthetypeofsoilneededforcultivationofcottonisavailableinselectedareasofIndiawhichlimitstheproductionofcotton.

23


Worksheet 1

1. (a)CottonandJute (b) Silkandwool

(c)Rayonandnylon (d) Sheepandcamel

2. (b),(d),(a),(e),(c)

3. (a)Naturalfibrelikecotton,(b)Syntheticfibrelikenylon,(c)Linen

Worksheet 1

1. (a)Takliandcharkha (b) Looms (c) Needles

2. (a)Syntheticfibre (b) Silk (c) Wool

(d)Cotton (e) Coir (f) Hemp

(g)Silk-cotton

3.(a) Punjab,Haryana,GujaratandRajasthan

(b) Bihar,Assam,AndhraPradesh,OrissaandMeghalaya

(c) Karnataka,AndhraPradesh,TamilNadu,WestBengalandJammuandKashmir

4. Cotton:Itrequiresblackoralluvialsoil,hightemperaturebetween21°Cand30°Candanannualrainfall

of50-100cm.

Jute:Hotandhumidclimate,hightemperature,heavyrainfallandlightsandyorclayeyloam.

24

Chapter 4Grouping Materials

Specific Learning Objectives Aft er the completion of the chapter, students will be able to: • Knowdifferentpropertiesonthebasisofwhichmaterialscanbeclassified. • Understandtheimportanceofclassification. • Applytheknowledgegainedinclassifyingagroupofsubstances. • Listexamplesoflustrousandnon-lustrous,transparent,translucent,opaque,miscibleand

immisciblematerials. • Distinguishbetweenconductorsandinsulatorsofelectricity.

Warm UpTh eWarmupexercisegivenonpage39isagoodexercisetostartthechapter.Askthestudentstoclassifythegivenlistofobjectsintodifferentgroupsonthebasisofcommonproperties.Oncetheyclassifyalltheobjects,askthemtousesomeotherpropertytoclassifythesameobjects.Th iswillmakethemunderstandthatthegroupingofmaterialsdependsonthepropertychosen.Forexample,apencil,asharpenerandabookcanbeplacedtogetherasstationaryitems,butapencilandabookcanbeplacedseparatelyfromasharpenerundermaterialsobtainedfromnaturalthings.

Concept Explanation • Appearance, lustre, hardness and roughness:Explainthesetopicstothestudentsbytaking

examplesfromeverydaylife,whichwouldappearfamiliartothestudents. • State:Explaintothestudentsthearrangementofmoleculesinthethreestatesofmatterwith

thehelpofdiagrams.Studentsshouldbemadefamiliartothepropertiesofsolids,liquidsandgasesbygivingthemacomparativeaccountofthethree.

• Solubility:Th etopiccanbewellexplainedtothestudentswiththehelpofExperiment1givenonpage43.Th iswillhelpthestudentstounderstandtheconceptinabetterway.Somestudentscanbeaskedtoperformthisactivitytocreateinterestintheclass.Th isisamethodoflearningbydoing.

• Transparency: Studentsmustbealreadyfamiliarwiththistopicastheyhavecoveredthisintheirpreviousclasses.Th is topiccanbestartedbyaskingthemquestions like;what isthe difference between glass sheet, butter paper and an iron object.Make the studentsunderstandthedifferencebetweenaglassandamirroronthebasisoftransparency.

• Magnetism, conduction of heat and electricity: Th ese topics are new to the students buttheymightbeknowingafewthingsfromtheirreallifeexperiences.Explaintothemtheimportanceofmagneticandnon-magneticsubstances,conductorsandinsulatorsofheatandelectricityindaytodaylife.

25

Reinforce • Goingthroughthedefinitionsgivenundertopic‘WordDrop’willhelpinaquickrecapitulation

asmanynewdefinitionshavebeenintroducedinthischapter.Askstudentstogiveexamplesofdifferentcategories.Anothermethodistogivethemalistofobjectsandaskthemtowriteany4-5propertiesoftheseobjects.Thiswillhelpindevelopingthinkingskillsamongthem.Completetheexercisesgivenatthebackofthechapter.

Explore • Students can learn further in the chapter by extending Experiment 1 given on page 43.

Studentscanfurtherextendtheirknowledgebycompletingtheprojectgivenonpage47.

26

Worksheet 1

1. Identify the property on the basis of which the following materials have been kept in two separate groups.

GROUP A GROUP B PROPERTY

(a) Gold,silverandiron Wood,clayandpaper

(b) Iron Sponge

(c) Glass,waterandair Frostedglassand Oilypatchonpaper

(d) Kerosene,water Oxygenandhydrogen and petrol

(e) Lemonjuice Sand,clayandsawdust andvinegar

2. Draw diagrams to show the arrangement of molecules in the given boxes.

SoapCake LemonJuice Oxygengas

3. Identify the state of matter being mentioned in the following statements.

(a) Ihaveafixedshape.

(b) Ihaveadefinitevolume.

(c) Myparticlesarenotverycloselypacked.

(d) Iamhighlycompressible.

(e) Icannotflow.

27

Worksheet 2 1. Give two examples of each of the following:

(a) Immiscibleliquids (b) Translucentmaterials

(i) (i)

(ii) (ii)

(c) Materialsthatfloatonwater (d) Magneticmaterials

(i) (i)

(ii) (ii)

(e) Insulatorsofheat (f) Conductorsofelectricity

(i) (i)

(ii) (ii)

2. Write any two properties of the following materials.

(a) Ironnail

(b)Water

(c) Plastics

(d) Sugarsolution

(e) Air

28


A. 1. (a) Oildoesnotdissolveinwater. (b) Liquidshavefixedvolumebutdonothavefixedshape. (c) Solidshavefixedshapeandsizesotheycannotoccupywhateverspaceisavailabletothem. (d) Paperboatwillnotsinkinwater. (e) Translucentmaterialsallowlighttopassthroughthempartially. 2. (a) Goldandsilver (b) Ironandcopper (c) Dryleavesandpaper (d) Stoneandbooks (e) Featherandcotton (f) AluminiumandcopperB. 1. Propertiesthatmaterialshave:

(a) Appearance (b) Hardness (c) Conductionofheatandelectricity (d) Solubility (e) Flotation (f) Transparency (g) Attractiontowardsamagnet (h) State (i) Roughness 2. Groupingofsubstanceshelpsinthestudyoftheirproperties.Substancesaregroupedonthebasis

ofappearance,state,hardness, transparency,etc.Th ishelps intheproperuseofmaterialonthebasisofitsproperties.

3. Th eparticlesinliquidsarenotcloselypackedduetowhichtheydonothavefixedshapebuttheyhavefixedvolume.

4. Oxygendissolvedinwaterisessentialforthesurvivalofaquaticorganisms. 5. (a)

Miscible liquids Immiscible liquidsLiquidsthatdissolveinwaterarecalledmiscibleliquids.Forexample:Vinegar,alcohol,etc.

Liquids that donot dissolve inwater are calledimmiscibleliquids.Forexample:Oil,petrol,etc.

(b)Lustrous material Non-lustrous material

Materialswhichhave shiny appearancearecalledlustrousmaterials.Forexample:gold,silver,etc.

Materials which do not have shiny appearancearecallednon-lustrousmaterial.Forexample:paper,plastic,etc.

(c)Conductor Insulators

Materialsthatallowheatandelectricityto pass through them are calledconductors.Forexample:Copper,iron,etc.

Materialsthatdonotallowheatandelectricitytopassthroughthemarecalledinsulators.Forexample:plastic,glass,etc.

29

(d)Transparent Translucent

Materials that allow light to passthrough them are called transparentmaterials.Forexample:air,cleanwater,etc.

Materials that allow light to pass through thempartiallyarecalledtranslucentmaterials.Forexample:butterpaper,frostedglass,etc.

6. Whenoilismixedwithwater,oilformstheupperlayerbecauseitislighterthanwater.C. 1. (a) Transparency: Property of materials that allows light to pass through them is called

transparency and the materials that shows this property are called transparent materials.Exampleoftransparentmaterialsareair,cleanwater,etc.

(b) Immiscible substances: Substances such as liquids thatdonotdissolve inwater are calledimmisciblesubstances.Forexample:oil,petrol,etc.

(c) Magnetism: Materialsthatareattractedtowardsamagnetarecalledmagneticmaterialsandthispropertyiscalledmagnetism.Exampleofmagneticmaterialsareironandnickel.

(d) Solubility: Thepropertyofvarioussubstancestodissolveinwateriscalledsolubility.Exampleofsolublesubstancesaresugar,salt,alcohol,etc.

2.Solids Liquids Gases

Compressibility Cannotbecompressed Cannotbecompressedeasily Can be highlycompressed

Volume Definite Definite NotdefinitePackingofparticles Closelypacked Not as closely packed as in

solidsLooselypacked

3. Threepropertiesonwhichmaterialscanbeclassified:

Property ExampleHardness (i)Copperishard,whilecottonissoft.

(ii)Glassishardwhilefeatherissoft.Solubility (i)Oilisnotsolubleinwaterwhile,vinegarissoluble.

(ii)Sanddoesnotdissolveinwater,whilesugardoes.Lustre (i)Goldislustrous,whilepaperisnot.

(ii)Silverislustrous,whilewoodisnot.D. Property 1. State 2. Hardness 3. SolubilityE. 1. LiquidCwillformthelowermostlayerandliquidBwillformtheuppermostlayer. 2. Suddendischarge of hotwater from industries intowaterbodies results in the death of aquatic

animalsbecauseconcentrationofdissolvedoxygendecreaseswiththeincreaseintemperature. 3. Ificecubesareaddedfirstinthewater,thesugarwillnotdissolveproperlyinthewaterassolubility

decreasesincoldwater.

30


Worksheet 1

1. (a) Lustre (b) Hardness (c) Transparency

(d) Solubilityandstate (e) Stateandsolubility

2.

Solid Liquid Gas

3. (a) Solid (b) Solidandliquid (c) Liquid

(d) Gas (e) Solid

Worksheet 2

1. (a) Keroseneandpetrol (b) Frostedglassandbutterpaper

(c) Leafandfeather (d) Ironandnickel

(e) Plasticandwood (f) Ironandcopper

2. (a) Conductorofelectricityandwillsinkinwater

(b) Liquidandconductorofheatandelectricity(notpurewater)

(c) Insulatorofheatandelectricityandtranslucent

(d) Liquidandtransparent

(e) Gasandinsulatorofheat

31

Chapter 5Separation of Substances

Specific Learning Objectives Aft er the completion of the chapter, students will be able to: • Listdifferentseparationmethods. • Explain different separation methods like handpicking, threshing, winnowing, sieving,

sedimentationanddecantation,filtration,evaporationandcondensation. • Understandtheimportanceofseparationofsubstances. • Understandtheprinciplebehindtheseparationmethods. • Acquireskillstoperformexperimentsusingsuitabletechniquesinthelab. • Identifythecomponentsinamixtureandseparatethemusingsuitablemethods. • Identifythesoluteandthesolventinagivensolution.

Materials RequiredTeaching Aids: Materialsthatcanbeusedtoexplainthistopicaretheonesrequiredtoperformexperimentslistedonpages50-55ofthebook.

Warm UpTh eclasscanbemadeinterestingbyaskingthestudentsquestionslike;howdoyouseparatemilkandcreamathome?Whatdoesyourmotherdobeforecookingrice?Th enstartthetopicwiththewarmupsectionofpage48.

Concept Explanation • Separating solids from solids:Explaintothestudentsthedifferentmethodscoveredunder

thistopic, i.e.,handpicking,threshing,winnowingandsievingwiththehelpofexamples.Th eexperimentsgivenonpages50and51canbeusedtoexplainthetopicinabetterway.

• Sedimentation, decantation and fi ltration: Th e topic can be started with the help ofExperiment3givenonpage52.Explaintothestudentsthemethodsofsedimentationanddecantation.Explain to themthat thisprocesscanbeusedonly for insoluble solids.Th esupernatantobtained inExperiment3canbe furtherpurified in frontof thestudentsbyusingtheprocessoffiltration.Takethestudents to the labtoshowtheprocess.Th iswillmaketheclassinteresting.Th eycanbegivenfilterpapersingroupstomakeacone.Th issimpleactivitywillmaketheclassinteresting.

• Evaporation and condensation: PerformExperiments 5 and 6 in front of the students toexplainthetopic.

• Solubility: Th e students already have an idea of the topic from their previous chapter.Studentscanbeaskedquestions likewhataresolubleandinsolublesubstances.Th eycanbeaskedto listsomeexamplesof the twocategories.Givethemtheconceptofsaturated

32

solutionbyexplainingtothemthatinsuchasolutionnomoresolutecanbedissolved.Thefactorsaffectingsolubilitycanbeshowntothemwiththehelpofanexperiment.

Reinforce • Thinkingabilitiesandvaluescanbedevelopedinthestudentswiththehelpofthe‘LifeSkill’

and‘Values’sectionsofthechapter.‘Sciencetip’givenonpage50isalsoimportantforthestudentstoknow.Suchinformationhelpsinthedevelopmentofscientificaptitudeamongthestudents.Thein-textexerciseandtheexercisesattheendofthechapterwillhelpthemtorefreshthechapter.Discussthenewtermsandtheirmeaningsgiveninthechapter.

Explore • Forextendedlearning,experimentsgivenonpage59ofthechaptercanalsobeperformedin

frontofthestudents.Studentscanfurtherextendtheirknowledgebycompletingtheproject.InformationgivenintheInnovator’sCornercanbeusedtoreinforcethelearningprocessinthestudents.

33

Worksheet 1

1. Identify the method of separation to be used to separate the following mixtures.

(a) Unwantedgrainsfromrice.

(b) Saltfromseawater.

(c) Stonesfromsandatconstructionsite.

(d)Grainsfromstalks.

(e) Lighterchaffparticlesfromheaviergrains.

(f) Oilfromwater.

2. Label the following diagram.

(a) Alsomentionthenameoftheprocess.

3. Fill in the blanks to complete the process of obtaining salt from sea water.

Sea water is collected in and it gets evaporatedby leavingbehindthesalt.Saltisthencollected,

andismadereadyforconsumption.

34

Worksheet 2 1. Arrange the following in proper order as they are followed during the removal of

impurities from a sample of rock salt. (a) Filterthesolution (b)Mixitwithwater (c) Puresaltisleftinthebeaker (d)Crushthesaltandconvertittoapowder (e) Allowsedimentation (f) Heatthefiltrateinabeakerandallowevaporation

2. Name two methods that can be used for each of the following: • Separatingsolidsfromsolids. __________________________ • Separatingsolidsfromliquids. __________________________

3. Identify the separation methods from the given pictures and name one mixture that can be separated using each method.

(a)

(b)

35


A. 1. (a) filtration (b) Supernatant,sediments (c) Residue (d) Solute (e) increases

2 . Column A Column B

Th reshing BeatingofcropstoseparategrainsfromstalksCondensation ChangingofvapoursintoliquidformEvaporation ChangingofwaterintovapoursSedimentation SettlingdownofheaviercomponentsinamixtureDecantation Transferofclearliquidaftersedimentation

B. 1. Separationofsubstancesisdonetoseparateusefulcomponentortoremoveundesirablecomponentsfromusefulmaterialortoobtainpuresampleofsubstance.

2. Saltisobtainedfromseawaterbytheprocessofevaporation. 3. Saturated solution into an unsaturated solution either by addingmore solvent in the saturated

solutionorheatingofsolution. 4. Sheuseshandpickingmethodtoremoveundesirablecomponentsfromrice. 5. No,itisnotpossibletoseparateamixtureofsaltandpowderedsugarbytheprocessofwinnowing

becauseonesubstancehastobelighterinweighttobecarriedawaybywind. 6. Solubility:Th eabilityofsubstancetodissolveinwateriscalledsolubility.Inasolutionofsugarand

water,sugarisasoluteandwaterisasolvent. 7.

Mixture Process of separationSand and water FiltrationOilandwater DecantationSalt from seawater EvaporationHuskfromgrains WinnowingStones from rice HandpickingSalt and water from their solution Condensation

C. 1. Manytimesonemethodisnotenoughtoobtainapuresubstance.Forexample:mixtureofsandandsaltisseparatedbythemethodoffiltrationandevaporation.Firstwaterisaddedinthemixtureofsandandsalt.Saltisdissolvedinwaterwhilesanddoesnot.Sandisseparatedfromsaltsolutionbythemethodoffiltration.Now,saltisseparatedfromwaterbythemethodofevaporation.Inthiswaymixtureofsandandsaltcanbeseparated.

2. (a) Handpicking:Th eprocessofremovingunwantedmaterialsbyhandandseparatingthem. (b) Winnowing:Th emethodofseparatinglighterparticlesfromheavierparticleswiththehelpof

windiscalledwinnowing. (c) Condensation:Th eprocessofconversionofvapoursintoliquidiscalledcondensation. 3. Processoffiltration: In the filtration process, unwantedmaterial is removed from solvent.On pouring themixture

throughfunnellacedwithfilterpaper,residueiscollectedinthefilterpaper,whilefiltrateiscollectedinthebeakerunderneaththefunnel.

36

ReferfiguregiveninExperiment4onpage52 4. Saturated solution:Solutioninwhichnomoresolutecanbedissolvediscalledsaturatedsolution. Saturatedsolutionofsugarcanbepreparedbyaddingsugarinwatertillitstopsdissolving. Whensuchsolutionisheateditbecomesunsaturatedagain. 5. Separationofwheatgrainsfromwheatplantsinvolvestwoprocesses. Threshing: Inthisprocess,wheatgrainsareseparatedfromthestalks.Itisdoneeithermanuallyor

withthehelpofmachines.Manualthreshingisdonebyholdingapileofcropandbeatingonahardsurface.Thisloosensandseparatesthegrainfromstalk.Itisalsodonebycrushingtheharvestedstalksusingbullocks.

Winnowing:Inthisprocess,lighterparticlesareseparatedfromtheheavierparticleswiththehelpofwind.Amixtureofgrainsandchaffisallowedtofallfromaheight.Thegrainsbeingheavierfallonthegroundwhilechaffpiecesbeinglighterarecarriedawaywiththehelpofwind.

D. First method is filtration which is used to separate the sand from salt water solution as salt is soluble in waterwhilesandisnot.Themixtureispassedthroughthefunnelcontainingfilterpaperwhichallowsthesaltsolutiontopassthroughitandsandisleftbehindastheresidueonfilterpaper.

Second method is condensation.Inthismethodsaltsolutionisheatedinakettle.Steamisformedwhichcomesoutfromthespoutofkettle,touchesthemetalplate,condensesandchangesintowaterdroplets.Thesewaterdropletsgetcollectedinthebeaker.Inthisway,saltisleftbehindinthekettlewhilewateriscollectedinthebeaker.

E. 1. Moresugargetsdissolvedinthehotwaterbecausesolubilityincreaseswithincreasingtemperature. 2. Separatingthemixtureofsand,sugarandironfilings: Firstofall,magnetisusedtoseparateironfilingsfromthemixture.Afterremovingironfilings,

water isadded in theremainingmixtureof sandandsugar.Onstirring thesolution, sugargetsdissolvedwhilesanddoesnot.Nowbyusingafilterpaper,sandisseparatedfromthesugarsolutionandfinally,bythemethodofevaporation,sugarisseparatedfromwater.

3. Due to rainfall, tinydust particles, smokeparticles andother suspendedpollutants getwasheddownasaresultofwhichvisibilityincreases.

4. Inasaturatedsaltsolution,nomoresolutewilldissolvebecausethesolutionisalreadysaturatedwithsaltparticlesandtherewillbenoroomforanyothersolutetogetdissolved.

37


Worksheet 1 1. (a) Handpicking (b) Evaporation (c) Sieving (d) Winnowing (e) Winnowing (f) Decantation 2.

Clearwater

Funnel

Filter paper

Mixtureofsand

and water

(a)Filtration 3. saltpans,sun’sheat,purified

Worksheet 2 1. (d),(b),(e),(a),(f),(c) 2. Sedimentationanddecantation,Filtration Evaporation,Condensation 3. (a)Winnowing. Separatinghuskfromgrains (b) Sieving Separatingsandfromgravelatconstructionsites

38

Chapter 6Changes Around Us

Specific Learning Objectives Aft er the completion of the chapter, students will be able to: • Knowthepropertiesofthedifferenttypesofchanges. • Givesomeotherexamplesofthedifferenttypesofchanges. • Understanddifferentchangesoccurringaroundthem. • Abletoclassifythesechangesasphysicalandchemical. • Analysethetermreversibleandirreversiblechanges. • Applytheknowledgegainedintheirdaytodaylife.

Materials Required

Teaching Aids:Th eproposedtopiccanbeexplainedwiththehelpofteachingaidslike;burningcandleandrubberballoons.

Warm UpAgoodwaytostartthechapterisbyaskingthestudentstolistsomechangesthattheyseearoundthem.Studentsmightbeabletosuggestchangeslike;dayandnight,growthofthebody,evaporation,burningofcandle,etc.NowaskthestudentstocompletetheWarmupsectionandActivity1.

Concept Explanation • Reversible changes:Explaintothestudentsthatsomeofthechangesthatweseearounduscan

bebroughtbacktotheirpre-changeorpreviousstate.Th esearetermedasreversiblechanges.Againtaketheexamplesgivenbytheminthewarmupsectionandselecttheexamplesthatbelongtothiscategory.Studentscanbeaskedtoreadtheotherexampleslistedonpage62andcanbeaskedtoexplainthechangeoccurringintheirownwords.

• Irreversible changes:Nowgothroughtheexamplesofirreversiblechanges(eitherfromthebookorifadifferentexampleistherethathasbeensuggestedbythestudentsatthebeginningofthechapter)andexplaintothemthattherearesomechangesthatcannotbebroughtbacktotheirpre-changeform.Th esearetermedasirreversiblechanges.AskthestudentstodoActivity2withtheknowledgegainedbythemsofar.

• Expansion and contraction: List the examples from the three states of matter to explainexpansionandcontractiontothestudents.Arubberballooncanbeusedtoexplainboththeprocesses.Watercanalsobeusedtoexplainthesame(Experiment2).Th iscanbeperformedinthesciencelabtomakethetopicmoreinteresting.

• Physical and chemical changes:Explaintothestudentsthatchangescanalsobeclassifiedasphysicalandchemicalchangesbasedonthepropertyoftheformationofanewsubstance.Manyexamplescanbegiventothemforbetterexplanation.

39

Reinforce

• Studentscanbegivenalistofchangesandcanbeaskedtoclassifythemasreversibleandirreversiblechanges.Suchanapproachhelpsin‘Learning by doing’.Thequestiongivenunder‘Breather’andattheendofthechapterwillhelpintherecapitulationofthetopic.Thinking skills canbedevelopedwiththehelpofquestionsgivenunderthe‘HOTS’section.

Explore • Studentscanlearnmoreaboutthechangeswiththehelpofactivitiesgivenundersections

‘Let’sspeak’,‘Innovator’sCorner’and‘Project’.Thesecanbedoneasagroupactivitytodevelopteamworksenseinthem.

40

Worksheet 1

1. Identify the following changes as reversible and irreversible.

(a) Increaseintheheartbeatrateafterjogging.

(b) Preparationoffoodbyplants.

(c) Cookingoffoodbyyourmother.

(d)Meltingofchocolate.

(e) Burningofcoaltogiveheatandlight.

(f) Inflatingordeflatingaballoon.

(g) Digestionoffood.

2. Give any two examples each where property of expansion and contraction in substances is used.

3. Complete the table to diff erentiate between physical and chemical changes.

Physical Changes Chemical Changes

41

Worksheet 2

1. Write an example where physical and chemical changes occurs simultaneously. Explain it.

2. Fill in the blanks to explain the process of fi tting an iron tool over wooden handle using the property of expansion and contraction of iron on heating and cooling respectively.

First, we the iron blade so that it and fits easily on the wooden handle. Th en the tool is dipped in cold water to

it so that it and fits tightly on thewoodenhandle.

3. Tick () the requirements for rusting of iron objects.

(a) Oxygen

(b) Carbondioxide

(c) Presenceofsaltsintheatmosphere

(d) Watervapourormoisture

(e) Nitrogen

(f) Alayerofoilontheironobject

42


A. 1. (a) Cuttingofvegetablesandtearingofpaper (b)Meltingoficecreamandinflationanddeflationofballoon (c) Cookingoffoodandburningofpaper (d) Growingofplantsandboilingofeggs 2. (a) Inaphysicalchange,nonewsubstanceisformed.

(b) Heatingofasubstanceresultsintheincreaseinitssize. (d)Wecannotgetbacktheproductsintheirpreviousforminanirreversiblechange. (e) Allphysicalchangesarenotirreversible.

B. 1. (a) Reversible change:Th echangewhichcanbereversediscalledreversiblechange. (b) Irreversible change:Th echangewhichcannotbereversediscalledirreversiblechange. (c) Physical change:Th echangeinwhichnonewsubstanceisformediscalledphysicalchange. (d) Chemical change:Th echangeinwhichnewsubstanceisformediscalledchemicalchange. 2. Gasesshowthemaximumcontractionandmaximumexpansion. 3. Th eairparticlescontractondecreasingthetemperature,thus,aninflatedballoonshrinkswhen

keptinarefrigerator. 4. Tearingofpaperisaphysicalchangeasnonewsubstanceisformedwhilethegrowthoflivingbeing

isachemicalchangeasitispermanentandchangeinmolecularstructureoflivingbeingoccurs. 5. (a) Gapsare left inbetween the railway tracks so that somespace isavailable for the tracks to

expandduringsummer. (b) Cooking of chapati from dough is a chemical change as it involves the formation of new

substanceanditisirreversibleinnature. (c) Heatfromhotwaterexpandsthebottleandwhencoldwaterispouredonit,duetosudden

contraction,bottlebreaks.C. 1. Refertablegivenonpage66 2. First,ironsmithheatstheironbladesothatitexpandsandfitseasilyinthewoodenhandle.Th enit

isdippedinthecoldwater,sothatitcontractsandfitstightlyontothewoodenhandle. 3. Metalrimismadeslightlysmallerthanthewheel.Onheating,itexpandsandfitseasilyintothe

wheel.Th encoldwaterispouredonthemetalrimanditcontractsandfitstightlyonthewheel. 4. Th reeapplicationsofexpansionandcontractionofmaterial:

(i) Liquid mercury expands in thermometer and rises up in the tube when the bulb ofthermometercomesincontactwithahotobject.

(ii) Ironbladesfittedonawoodenhandlewhilemakingtools. (iii) Rubber tyre ismade slightly smaller in size than thewheel.Th e tyres areheated, they

expandandfiteasilyonthewheel.Th enthetyreisallowedtocooldownsoitcomesbacktoitsoriginalsize.

5. Allphysicalchangesarenotreversibleinnature.Forexample,tearingofpaperintosmallpiecesisaphysicalchangebutnotreversibleasonecannotchangepiecesintopaper.

6. Duringtheconversionoficeintowater,nochangeinthemolecularstructureisobservedandnonewsubstanceisformed.Hence,conversionoficeintowaterisnotachemicalchange.

D. Peelinganapple:PhysicalandirreversiblechangeMakingaclaypot:ChemicalandirreversiblechangeBurningofcandle:Chemical,physicalandirreversiblechange

43

E. 1. Heat produced fromhotwater forces the glass particles to expand due towhich glass tumblerbreakswhenhotwaterisaddedtoit.

2. Doughismadebymixingwaterinflour,sonochangeisobservedinmolecularstructure.Hence,it is a physical change.Cooking of chapati fromdough is a chemical change as it involves theformationofnewsubstanceanditisirreversibleinnature.

3. Burningofcandleinvolvesbothphysicalandchemicalchangesasonburning,waxmeltswhichcanbesolidifiedagain.Alsoburningwaxconvertsintovapourstatewhichcontinuestoburnandgiveheatandlight.Soburningofwaxinvolvesbothphysicalandchemicalchanges.

4. Makingofcurdfrommilkisanirreversiblechangeascurdisformedduetotheactionofyeastonmilkwhichcannotbereversed.


Worksheet 1 1. (a)Reversiblechange (b) Irreversiblechange (c) Irreversiblechange (d) Reversiblechange (e) Irreversiblechange (f) Reversiblechange (g) Irreversiblechange 2. Expansion: (i)Gapsareleftbetweentworailwaytracks (ii)Increaseinthesizeofinflatedballoonwhenkeptinthesun Contraction:(i)Leavingthecablewiresloosewhilelayingthemdowninsummers (ii)Decreaseinthesizeofballoonwhenkeptintherefrigerator 3.

Physical change Chemical change

Nonewsubstanceisformed. Anewsubstanceisformed.

Th esechangescanbereversedeasily. Mostofthechemicalchangesareirreversible.

Th ischangeistemporary. Th ischangeismostlypermanent.

Th ereisnochangeinthemolecularstructureofthesubstance.

Th esubstanceundergoesachangeinitsmolecularstructure.

Forexample,breakingofaglass Forexample,cookingoffood

Worksheet 2 1. Burningofcandleinvolvesbothphysicalandchemicalchangessimultaneously.Whenweburnacandle,

thewaxmeltsandthisliquefiedwaxcontinuestoburnfurtherandconvertsintogaseousstate.Th us,vaporizedwaxburnstogiveheatandlight.

2. Heat,expands,cool,contracts 3. (a),(d)

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Chapter 7Living and Non-Living Things

Specific Learning Objectives Aft er the completion of the chapter, students will be able to: • Distinguishbetweenlivingandnonlivingthingsandbioticandabioticcomponents • Recognizedifferentfeaturesoflivingbeings • Describe these features in their own words • Explaindifferentbioticandabioticcomponentsoftheenvironment • Learn about hot and cold blooded animals • Understand terms like biotic community, scavengers, decomposers, sensitivity andmany

others

Warm UpTh estudentsareawareofthefactthathumans,animalsandplantshavefeaturesthataredifferentfromotherthings liketable,water,soil,airaroundthem.Hence,weclassifyhumans,plantsandanimalsaslivingandothersasnon-living.Th eymightalsobeawareofsomecharacteristicsshownbylivingthings.Onthebasisoftheseaskthemtocompletetheexercisegivenunder ‘Warmup’section.

Concept Explanation

• Living things are made up of cells:Explaintothestudentsthedifferencebetweenunicellularandmulticellularorganisms.Th ecellularorganisationshouldalsobecovered.

• Living things can move, grow, reproduce, excrete and respire:Th e different characteristicsof the livingorganisms shouldbecovered.Cover these topicswith respect toplants also.Newtermslikeautotrophs,heterotrophs,reproduction,excretion,andrespirationshouldbeexplainedtothem.Th eirdefinitionsshouldbediscussed.Respiratoryorgansinsomeotherorganismsmayalsobementioned.

• Response to stimuli:Manyexamplesshallbediscussedtoexplainthetopictothestudents.Firstgivefewexamplesandexplaintheresponseandstimuliinthoseexamplestothem.Th eclasscanbemadeinteractivebyaskingthestudentstoidentifystimuliandresponseinsomeexamplesgivenbyyou.

• Biotic components:Th edifferentbioticcomponentsbasedonthemethodofobtainingfoodshouldbe listed and explained to the class. Studentsmust alreadybe familiarwith termslike herbivores, carnivores, omnivores, scavengers and decomposers form their previouschapters,sotheyshouldbeaskedtoexplaintheseterms.Th iswillmaketheclassflowinaninteractiveandhealthyway.

• Abiotic components: Differentabioticcomponentsalongwiththeirimportancetothebioticworld shouldbecovered in theclass.Explain to the studentshow these twocomponentsinteractwitheachothertoresultinasuccessfulenvironment.

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Reinforce • Thechapterintroducesmanynewtermsandtheseshouldberepeatedwiththehelpofthe

‘WordDrop’section.Thechapteralsoincludesfewactivitiesthatwillhelptodevelopvaluesamong the students.Ask the students to complete the exercises given in the chapter anddiscusstheanswerstothequestionswiththem.Makethestudentsunderstandtheimportanceoftreesinourlife.Thiswillhelpindevelopmentof‘Love towards the environment’.

Explore • Theactivitiesmentionedunder‘Let’sspeak’and‘Project’sectionscanserveasaformative

assessmentproject.Theexperimentmentionedinthe‘Innovator’scorner’canbeperformedinthelabforbetterunderstandingamongthestudents.

46

Worksheet 1 1. Give two examples for each of the following:

(a) Unicellularorganisms (b) Egglayinganimals

(i) (i)

(ii) (ii)

(c) Scavengers (d) Multicellularorganisms

(i) (i)

(ii) (ii)

(e) Decomposers (f) Heterotrophs

(i) (i)

(ii) (ii)

2. Complete the following sequence for showing the level of organisation. Cells Organism

3. Write the requirements for photosynthesis. Also mention, why green plants are called autotrophs?

47

Worksheet 2 1. Select the response and the stimuli from the following. (a) Wateringofmouthonseeingdeliciousfood. (b) Curlingofleavesof‘Touch-me-not’plantontouching. (c) Movementofplantroottowardswater. (d)Cockroachesrunawaytotheirhidingplaceswhenlightofthekitchenisswitched

onatnight. (e) Stemofaplantgrowstowardslight.

2. Tick () the abiotic components of the environment.

(a) Air

(b) Decomposers

(c) Treesinaforest

(d) Soil

(e) Waterorhumidity

(f) Sunlight

(g) Animals

3. (a) WhatareAandB? (b)WhatprocessesareinvolvedinreleasingAandB?

HumansandOtherAnimals

Releases‘B’

Releases‘A’

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A. 1. (a) Henandant (b) Amoeba and bacteria (c) Whalesandhumanbeings (d) SunflowerandMimosa (e) Animalsandbirds (f) Reptilesandfishes 2. (a) unicellularorganisms (b) response (c) plantsandanimals (d) cold-bloodedanimals

B. 1. (a) Living things Non-living things

Th ey are made of cells. Th ey can move,reproduce andgrow.Th eyneed foodandairtostayalive.Th eyexcreteandhavealifespan.

Th eyarenotmadeofcells.Th eydonotmove,reproduceandgrow.Th eydonotneedfoodandairtostayalive.Th eydonotexcreteanddonothavealifespan.

(b)

Autotrophs HeterotrophsAutotrophs are those which can prepare their ownfood.Forexample:plants

Heterotrophs are those which depend onautotrophsdirectlyorindirectlyfortheirfood.Forexample:animals

(c)

Organ Organ systemA group of tissues performing a particularfunctioninthebodyformanorgan.Forexample:Ear,eyes,etc.

Agroupoforgansinteractingwithoneanothertoperformaprocessinthebodyformanorgansystem.Forexample:digestion,respiration,etc.

(d)

Biotic components Abiotic componentsItisthelivingcomponentoftheenvironment.Forexample:plantsandanimals

Itisthenon-livingcomponentoftheenvironment.Forexample:air,water,sun,etc.

(e)

Unicellular organisms Multicellular organismsOrganismsthataremadeupofonlyonecellwhichperformsallthefunctions.Forexample:Amoeba,bacteria,etc.

Organisms that aremade up ofmore than onecell.Forexample:animalsandplants

(f)

Cold-blooded animals Warm-blooded animalsAnimalswhosebodytemperaturechangeswithtemperatureoftheirsurroundings.

Forexample:insects,reptiles,etc.

Animals whose body temperatureremains constant and does not changeaccordingtosurroundings.Forexample:mammalsandbirds

2. Th erearenocommoncharacteristicsthatareobservedinbothlivingandnon-livingthings. 3. Requirementsforseedgerminationarepresenceofsunlight,moistureinthesoilandair. 4. Ifwasteisnotexpelledfromthebody,itcreatesproblemsinthebodywhichcreatehealthissues.

49

5. Stomatahelpsintheremovalofwatervapour,carbondioxideandoxygen. 6. Animalsaredependentonplantsfortheirfoodwhileplantsdependonanimalsforcarbondioxide

whichisusedbytheplantsasoneofthecomponentsformakingtheirfood.C. 1. (a) Stimuli: Changesintheenvironmentwhichmaketheorganismrespondtothemarecalled

stimuli. (b) Reproduction: Thebiologicalprocessinwhichanorganismproducesbabyofitsownkindis

calledreproduction. (c) Excretion: Theprocessofremovingwastefromthebodyiscalledexcretion. (d) Respiration: Thefoodeatenbytheorganismisbrokendownintosimplersubstancesinthe

presenceofoxygentoreleaseenergyandcarbondioxideiscalledrespiration. (e) Species: Thegroupoforganismshavingthesamecharacteristicsandfeaturesiscalledspecies.

Theyreproducebabiesoftheirownkindandcontinuetheirspecies. (f) Ecology: Thestudyoftherelationshipbetweenlivingthingsandtheirenvironmentiscalled

ecology. 2. Animalsshowmovementfromoneplacetoanotherbecauseofthefollowingreasons:

(i) Insearchoffoodandshelter (ii) Toprotectthemselvesfromtheirenemiesandpredators (iii) Toprotectthemselvesfromadverseclimaticconditions 3. Characteristicsoflivingbeings

(i) Livingthingsshowgrowthastheyincreaseinsizeandheight. (ii) Livingthingssuchasanimalscanmovefromoneplacetoanother. (iii) Livingthingscanreproduce. (iv) Livingthingsrespire. (v) Livingthingsneedfoodandairtostayalive. (vi) Livingthingshavealifespan. (vii) Livingthingsshowresponsetothechangesintheenvironment. (viii) Livingthingsexcreteoutwastefromtheirbody. 4. Abioticcomponentsofenvironmentareair,water,sunlight,soilandtemperature. Sunlight:Itisusedbyplantsasoneofthecomponentstomaketheirproduce.Italsoincreasesthe

temperatureofthearea.Lifeexistsontheearthbecauseithassuitabletemperaturerangeforallthelivingbeings.

Air:Itisusedbylivingthingstosurvive.Asanimalsusedoxygentorespirewhileplantsusecarbondioxidetomaketheirfood.Movingairorwindalsohelpsinpollinationanddispersalofcertainfruitsandseeds.

Water:Livingthingsneedwatertodrink.Plantsabsorbwaterthroughtheirrootswhichalsoabsorbmineralsalongwithwater.Alsowaterisamajorcomponentofbloodwhichtransportmaterialsintheanimalbody.

5. Bioticcomponentsofenvironmentare (i) Plants:Theyareautotrophs,i.e.,theymaketheirownfoodbytheprocessofphotosynthesis.

Theyarealsotermedasproducers. (ii) Animals:Theyareheterotrophs,i.e.,theydependdirectlyorindirectlyonplantsfortheirfood.

Theyarealsocalledasconsumers.Onthebasisoftheirfeedinghabotstheyarecategorisedintoherbivores,carnivoresandomnivores.

(iii) Scavengers:Theyfeedonthedeadbodiesofotheranimals.Theyhelpinkeepingenvironmentclean.

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(iv) Decomposers:Th eyare themicroorganisms thatacton thedeadremainsofplantsandanimalsandreleasethenutrientsbackintothesoil.Th eymaintainthebalanceinthesoilbyrecyclingthenutrients.

6.

Stimulus ResponseScentofflowers AttractionSun MoveMoisture MoveColdtemperature Curlingofleaves

D. (i) Respondtostimuli (ii)Excretion (iii)GrowthE. 1. Th eprocessofphotosynthesisrequiressunlight,water,carbondioxideandchlorophyllpresentin

greenleaves.Althoughplantsrespirethroughoutthedaybutduringthenighttime,sunlightisnotavailablewhichstopstheprocessofphotosynthesisinplants.

2. Besides growth, human beings show other characteristics such as respiration, reproduction,responsetostimuli,excretion, locomotion,etc.Th esecharacteristicsarenotshownbybuilding,thusitisconsideredasnon-livingthing.

3. Duringtheprocessofphotosynthesis,plantstakecarbondioxidepresentinairtomaketheirfoodandtheygiveoutoxygenastheby-product.Soplantsareconsideredassupplierofoxygen.

4.

Scavengers Decomposers

Animals that eat the dead remains of other animals which are left behind after carnivores have fed on them arecalledscavengers.Forexamples:vulturesandhyenas.

Microorganismsthatactonthedeadremainsofplantsand animals and release the nutrients back into thesoil.Th eymaintainthebalanceinthesoilbyrecyclingthenutrients.Forexample:bacteriaandfungi


Worksheet 1 1. (a)Amoeba and Paramecium (b) Insectsandfish(c)Hyenaandvulture (d) Humansandplants (e) Bacteriaandfungi(f)Animalslikelionsandtigers 2. Tissue,Organ,Organsystem 3. Requirementsforphotosynthesis:Sunlight,chlorophyll,carbondioxideandwater Greenplantscanpreparetheirownfoodbytheprocessofphotosynthesis,sotheyarecalledautotrophs.

Worksheet 2 1. (a) Response-Wateringofmouth,Stimuli-Deliciousfood (b) Response-Curlingofleaves,Stimuli-Touch (c) Response-Movement,Stimuli-Water (d) Response-Runaway,Stimuli-Light (e) Response-Grow,Stimuli-Light 2. (a),(d),(e)and(f) 3. (a) A-OxygenandB-Carbondioxide (b)A-PhotosynthesisandB-RespirationandIndustries

51

Chapter 8Plant and their Parts

Specific Learning Objectives Aft er the completion of the chapter, students will be able to: • Knowthefunctionsofdifferentpartsofaplant. • Telldifferencebetweenthetwotypesofrootsandtypeofleafvenation. • Identifydifferentpartsofaleafandaflower. • Demonstrate some of the functions of different parts of a plant like stem conduction,

photosynthesisandtranspiration. • Analysedifferenttermslikevenation,pollinationandreproduction.

Materials RequiredTeaching Aids:Anumberofteachingaidscanbeusedfortheproposedchapterlikeplantspecimensto show- different types of roots, rootmodifications, stemmodifications, leafmodifications, atypical leaf tostudy itsstructure,aflower,seeds toshowcotyledons.Apart fromthis,materialsrequiredtodemonstrateExperiments1-4mentionedinthechapter.

Warm UpStudentsarealreadyfamiliarwithdifferentpartsoftheplantandthemainfunctionoftheseparts.Th eyalsohaveknowledgeofpollinationfromtheirpreviousclasses.SotheWarmupsectionofpage83willhelpinrecapitulation.

Concept Explanation

• Th e root system:Explain to thestudents thebasic structureofa rootandhowa taprootdiffersfromafibrousone.Acomparativeaccountofthetwocanalsobegiveninatabularform.FunctionoftherootcanbedemonstratedwiththehelpofExperiment1.Differentrootmodificationswiththeirfunctionsshouldalsobecovered.

• Stem:Experiment2shouldbesetinfrontoftheclassadaybeforestartingthementionedtopic. Students should be shown the result of the experiment and functions of the stemshouldbediscussedwith them.Differentstemmodificationswith their functionsshouldalsobetaught.

• Leaves:Studentsshouldbeexplainedthetwotypesofleafvenationandthestructureoftheleafwiththehelpofleafspecimens.Eachstudentcanbeaskedtobringhis/herownmaterialtostudyaleafandalsotoshowtheprocessoftranspirationintheplants.Th iscanbecoveredasagroupactivityalso to inculcate teamwork skills in students.A temporarymountofstomatacanbeshowntotheminthesciencelab.

• Flower:SpecimenofflowerslikeChinarose,tulips,rose,etc.canbeusedtostudypartsofaflower.Studentsshouldbeaskedtobringtheirownspecimen.Th iswilldevelopinterestinthem.Tellstudentsabout theflowers that theyshouldavoidtostudypartsofaflower

52

(sunflower,marigold).The terms likepollination, reproductionandcotyledons shouldbeexplainedtothem.

Reinforce • Students shouldbeaskednot topluckflowersordestroy theplants.Activitiesmentioned

under topic ‘life skills’ and ‘values’ could behelpful in imparting ‘value education’ to thestudents.Askthestudentstocompletetheintextandbackquestionsanddiscusstheanswerswiththem.HOTSquestionswillhelpindevelopingthinkingskillsinthem.

Explore • Studentscaneasilyperformsomeoftheactivitiesmentionedinthechapterathome,likestem

conduction.Askthemtostudypartsofaflowerfromanythreedifferenttypesofflowers.Theactivitiesmentionedunder ‘Innovator’scorner’and‘Project’canbeusedasformativeassessmentactivities.

53

Worksheet 1

1. Mention any two of the following.

(a) Leafvenation

(b) Plantsystems

(c) Roots

(d) Pollination

2. Match the Columns:

COLUMN A COLUMN B

Root Transpirationthroughstomata

Stem Reproduction in plants

Leaves Conductionofwaterandminerals

Flowers Absorbingwaterandminerals

3. Give two examples for each of the following.

(a) Storageroots (b) Storagestem

(i) (i)

(ii) (ii)

(c) Insectivorousplants (d) Reproductiveroots

(i) (i)

(ii) (ii)

54

Worksheet 2 1. Name the part of the fl ower being mentioned in the following statements. (a) Itcontainsthepollengrains. (b) Femalereproductivepart. (c) Attractsinsectforpollination. (d) Bead-likestructuresintheovary. (e) Topmostpartofthecarpelthatreceivesthepollens. (f) Stalkoftheflower. (g) Protectsthebud.

2. Label the marked parts in the leaf.

3. Name the part of the plant that is modifi ed in the following plants. (a) Th ornsinroseplant (b) Additionalsupportinbanyantree (c) Tendrilsinapeaplant (d)Tendrilsingrapevines

55


A. 1. (a) Ovules (b) Parallelvenation (c) Dahlia (d) Pea (e) leaves 2. (a) Neemandcarrot (b) Sweetpotatoandturnip (c) Wheatandrice (d) Potatoandginger (e) Wheatandmaize (f) Bryophyllumandcactus (g) Roseandmango (h) Venusflytrapandpitcherplant

B. 1. Aplantiscategorisedintorootsystemandshootsystem. 2. Suchrootiscalledthetaprootwhichhasonethickmainrootthatgrowsdeepintheground.Itis

differentfromtherootsofgrasseswhichhavefibrousroots.Fibrousrootshavemanythinfibre-likerootsthatgrowfromthebaseofthestemandspreadundersoilhorizontally.Fibrousroothasbushyappearanceandhasnosinglemainroot.

3. Desertplantshavespinesinsteadofleavessothatthelossofwaterthroughleavesisminimisedasthereisscarcityofwaterinthedesertarea.

4. Advantagesoftranspiration: (i) Itcoolsdowntheplantsandprotectsthemfromheatinjury. (ii) Lossofwatermakestherootstoabsorbmorewateralongwithnutrientsfromthesoil. (iii) Italsoplaysanimportantroleinwatercycle. Disadvantageoftranspiration: Astranspirationisalossofwaterfromtheplantthroughleaves,itisnotsuitablefortheplantsin

desertareaswherethereisascarcityofwater. 5. Importance of fl ower: Itisthemostattractiveaswellasthereproductivepartofplant.Ovaryofthe

flowerturnsintofruitwhileovuleschangeintoseeds. 6. (a) Th eadditionalsupporttoabanyantreeisprovidedbyitsroots.

(b) Stemgivessupporttotheplant. (c) Ovuleistheinnermostpartoftheflower. (d)Th elossofwaterfromthestomataiscalledtranspiration. (e)Th eediblepartofthepotatoisthestem. (f) Petalsarethecolourfulpartoftheplant. (g) Carpelofaflowerconsistsofstigma,styleandovary. 7. (a)

Parallel venation Reticulate venationTh eveinsrunparalleltoeachotherfromthebasetothetipoftheleaf.It is usually found in plants with fibrousroots.Itisfoundinleavesofwheat,maize,rice,etc.

Th e veins are arranged in a net-like patternsurroundingthemidrib.Itisusuallyfoundinplantswithtaproots.Itisfoundinleavesofradish,carrot,rose,etc.

56

(b)Stamen Pistil

Itisthemalereproductivepartoftheplant.

Itconsistsoffilamentandanther.

It is the female reproductive part of theplant.Itisalsoknownascarpel.Itconsistsofstigma,styleandovary.

C. 1. (a)Functionsofroots: (i) Itabsorbswaterandothernutrientsfromsoilforthegrowthoftheplant. (ii) Itanchorstheplant. (b) Functionsofstem: (i) Itsupportstheplantandkeepsitupright. (ii) Ithelpsintransportingwaterandothernutrientsfromrootstoallthepartsoftheplant. (c) Functionsofleaves: (i) Theypreparefoodbytheprocesscalledphotosynthesis (ii) Theylosewaterfromtheleavesbytheprocessoftranspiration. 2. (a) Transpiration: Theprocessoflossofwaterfromtheplantsthroughleavesiscalledtranspiration.

(b) Photosynthesis:Theprocessbywhichplantsmaketheirfoodwiththehelpofsunlight,air,water,chlorophyllpresentinleavesandnutrientspresentinsoiliscalledphotosynthesis.

(c) Venation:Thearrangementofveinsinaleafiscalledvenation. (d) Pollination:Theprocessoftransferringpollengrainsfromanthertostigmaofeitherthesame

flowerorofanotherflowerofthesamekindiscalledpollination. 3. Twotypesofvenationfoundinplantsare:

(i) Parallel venation: Theveinsrunparalleltoeachotherfromthebasetothetipoftheleaf. Itisfoundinleavesofwheat,maize,rice,etc.Itisusuallyfoundinplantswithfibrousroots (ii) Reticulate venation: Theveinsarearrangedinanet-likepatternsurroundingthemidrib. Itisfoundinleavesofradish,carrot,rose,etc.Itisusuallyfoundinplantswithtaproots 4. Threetypesofrootmodification:

(i) Rootsofplantssuchasmangrovesriseabovethegroundforbreathing. (ii) RootsofplantssuchasCuscutaabsorbsnutrientsfromthehostplant. (iii) Rootsofplantssuchasdahliacandevelopintoanewplant. 5. Twoexamplesofstemmodification:

(i) Stemsofcertainplantscanbeusedtogrownewplants.Forexample:roseandjasmine. (ii) Insomeplants,stembecomesfleshytostorewater.Forexample:cactus. 6. (a)Totestthepresenceofstarchintheleaves.

Firstweneedtoboiltheleaffor10minutes.Afterthatleafistakenoutandplacedinatesttubecontainingalcohol.Thenwateristakeninthebeakerandtesttubecontainingleafisputinthebeaker.Nowbeakerisheatedtilltheleafdecolourises.Afterthis,leafistakenoutandwashedwithwater.Now2-3dropsofiodinesolutionareputonleafwhichgivesblueblackcolourtoit.Thisindicatesthepresenceofstarchintheleaf.

(b) Totesttheroleofrootsinabsorptionofwater: Forthiswetake2plantsandrootsofoneplantiscutwiththescissors.Nowboththeplantsare

plantedintwoseparatepotsfilledwithsoil.Plantsarewateredregularlyforaboutaweekandafteraweekwewillfindthattheplantwithrootslookshealthywhiletheplantwithoutrootslookspale.Thisshowsthatrootsabsorbswaterfromthesoil.

57

7. Structureofleaf: Midrib:Th ickandthelongestveinpresentinthemiddleoftheleaf.Itisnotpresentingrasses. Vein:Ithelpsinthetransportationoffood,waterandmineralswithintheleaf. Lamina:Itisalsoknownasleafblade.Itistheflat,broad,greenpartoftheleaf. Petiole:Itisthethinstructurethatconnectstheleaftothestem. ReferFigure8.15frompage88

D. ReferFigure8.20frompage92E. 1. If the leaves have parallel veins then the plant has fibrous roots and if the leaves have net-like

structuredveinsthentheplanthastaproot. 2. Incasetherateoftranspirationishigherthanrateofwaterabsorptionbyrootsthenduetoexcess

lossofwaterplantwilldie. 3.

Fruit VegetableItisthematuredovaryofaflower.It has seeds which plays an important role inreproduction.

Itistheediblepartoftheplant.Itmayormaynothaveseeds.

4. Stomatahelpsintherespirationprocessoftheplantandalsowaterislostthroughit.Iftherearemore stomata on the surface of leaf than the underside then due to direct contact with sun, loss of waterwilltakeplacerapidlywhichwouldcausedehydrationinplant.

5. Whenasteelplateandapottedplantarekeptinthesunlightforafewhours,steelplatebecomeshotwhileplantdoesnot.Th isisbecauseoftheprocessoftranspirationwhichhelpsinkeepingtheplantcoolandprotectsitfromtheheatinjury.


Worksheet 1 1. (a)Parallelandreticulate (b) Rootsystemandshootsystem (c)Tapandfibrous (d) Selfandcross

2. Root—Absorbingwaterandminerals,Stem—Conductionofwaterandminerals,Leaves—Transpirationthroughstomata,Flowers—Reproductioninplants

3. (a)Carrotandradish (b) Potatoandginger (c) Flytrapandpitcherplant(d) DahliaandAsparagus

Worksheet 2

1. (a)Anther (b) Carpelorpistil (c) Petal (d)Ovules (e) Stigma (f) Pedicel (g) Sepal 2. Leafblade/lamina

Midrib

Petiole

Veins

3. (a)Leaves (b) Roots (c) Leaves (d) Stems

58

Chapter 9Body Movements

Specific Learning Objectives Aft er the completion of the chapter, students will be able to:

• Understand the difference between vertebrates and invertebrates, exoskeleton andendoskeleton.

• Appreciatetheimportanceofskeletalsysteminourbody.• Giveinformationaboutsomepartsoftheskeletalsysteminhumanbody.• Understandthelocomotionindifferentanimals.• Gainknowledgeonhowmusclesandboneswork together tobringaboutmovement in

body.• Listdifferenttypesofjointsinhumanbody.

Materials Required

Teaching Aids:Ahumanskeletonifavailableinschoolsciencelabcanbeusedtostudydifferenttopicsmentionedinthechapter.

Warm UpTomaketheclassinteractive,startthetopicbyaskingquestionslikewhatdoyoumeanbymovementorlocomotion?Whathelpsinthemovementofourbody?Isthemovementindifferentorganismssame?Ifno,suggestsomeexamplesofdifferentanimalmovements.Discusstheanswerstothesequestionsintheclass.Now,askthestudentstocompletetheWarmupsection.

Concept Explanation • Skeleton:Explainthedifferencebetweenthevertebratesandtheinvertebratestothestudents.

Alsoexplainto themhowexoskeletonandendoskeletondiffer fromeachother.Let themanswertheimportanceofskeletoninhumanbodyanddiscusstheanswersgivenbythemintheclass.Lettherebeatwowayinteractionintheclass.

• Parts of the skeleton:Differentboneslikeskull,ribcage,limbs,vertebralcolumnshouldbediscussedwithstudents.Remainconfinedtotheknowledgethatshouldbeimpartedtothematthislevel.

• Joints:Movementofthejointscanbeshowntothestudentsintheformofavideoifavailable.Th iswillhelpinthedevelopmentof‘Learningbyseeing’;otherwise,simplebodymovementswillalsohelpthemtounderstanddifferentbodyjoints.

• Movement in diff erent animals:Movement in different animalsmentioned in the chaptershouldbediscussedintheclass.Explaintotheclasshowthesemovementsdifferfromeachotherandwhatspecificfeatureintheorganismhelpsittobringaboutthesemovements.Trytogivestudentsacomparativeaccountofthesedifferentmovements.

59

Reinforce • Theactivitiesmentionedunderthesection'Values'and'Lifeskills'willhelptoimpartvalue

education and love for natureamongstudents.TheonegivenintheLifeSkillsectiononpage104canbeusedasa formativeassessment topic.Thiscanbeusedasan interdisciplinaryactivityalongwithsocialscience.Thequestionsmentionedinthechaptershouldbediscussedwiththestudents.Thischapterincludesmanypointsthatwillhelpthestudentstounderstandtheimportanceofexercises,yogaandbalanceddietinmaintainingagoodhealth.

Explore • Studentscanbeaskedtonamethe jointpresent indifferentpartsof thebodyapart from

the examples given in thebook.They canbe asked to judge themselves thatwhichbodypartshowsmaximummovementandwhichoneshowsmovementinonedirectiononly.Ahumanskeletoncanbeusedforthisactivity.

60

Worksheet 1 1. Match the Columns.

COLUMN A COLUMN BSkull ProtectsheartandlungsRibCage MadeupofmanysmallbonesBackbone Ithasonlyonemoveablebone,i.e.,lowerjaw

2. Identify the joint pesent in the parts of the skeleton marked in the diagram.

(a) ______________

(b) ______________

(c) ______________

3. Diff erentiate between upstroke and downstroke movements in birds.

61

Worksheet 2 1. Give two examples for each of the following.

(a) Invertebrates (b) Animalswithendoskeleton

(i) (i)

(ii) (ii)

(c) Animalswithexoskeleton (d) Vertebrates

(i) (i)

(ii) (ii)

2. Identify the type of joint present in the following body parts. (a) Kneejoint (b) ElbowJoint (c) ShoulderJoint (d)WristJoints

3. Match the organism with its feature.

COLUMN A COLUMN B

Birds Limblessvertebrates

Snakes Segmentedbody

Snails Streamlinedbody

Fishes Hollowandlightbones

Earthworms Haveanexoskeleton

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A. 1. (a) Endoskeleton (b) Invertebrates (c) Hingejoint (d) Earthworm (e) Ribcage 2. (a)(i) (b) (i) (c) (iv) (d) (iii) (e) (ii)B. 1. Disclaimer:Locationsandexamplesaresame.

Diff erent types of joint Location/ExampleBall-and-socketjoint JointatthehipandshoulderHingejoint Knee,elbowandfingerjointPivotjoint NeckisjoinedwiththeheadGlidingjoint Jointsinankleandwrist

2. Th efixedjointssuchasskullinourbodydonotallowanymovementastheyprovideprotection. 3. Twofeaturesofbirdthathelpthemtoflyare:

(i) Hollowandlightbonesreducetheirbodyweight. (ii) Breastbonesofbirdsarestrongandenlargewhichprovideasurfaceforattachmentofflight

muscleswhichenablesthemtofly. 4. Th elowerbodypartoftheearthwormhashair-likestructuresthathelpittofixitselfontheground

duringthemovement. 5. Th ebodyofthesnailproducesslimethatmakesthesurfaceslipperyandhelpssnailinitsmovement. 6. Earthwormhasliquidskeletonsystem.Itisinvertebrateandhasnobones.C. 1. Functionsperformedbyskeleton:

(i) Itprovidessupporttothebodyandgivesitapropershape. (ii) Ithelpsinthebloodcellformation. (iii) Ithelpsinthemovementofdifferentbodyparts. (iv) Itactsasastorehouseforcalciumandphosphorus. (v) Itprovidesasurfacefortheattachmentofmuscles. (vi) Itprotectsthedelicateorgansofthebody,suchaslungs,heartandbrainsfromdamage. 2. Varioustypesofjointsandtheirrole:

(i) Ball-and-socket joint:Inthistypeofjoint,theroundedheadofonebonefitsintothehollow,cup-shapedsocketofanotherbone.Th isallowsmaximummovementofthebodyparts.

(ii) Hinge joint:Th isjointprovidesbackandforthmovementsimilartothehingeofadoor. (iii) Pivot joint:Inthisjoint,acylindricalbonerotatesinsidearing-shapedbone. (iv) Gliding joint:Th isjointallowsthebonestoglideovereachotherandfacilitatesmovementin

alldirections. 3. (a) Skull:Skullisthefixedjointorimmovablejointwhichprovidesprotection.

(b) Backbone: Th e longbonystructureat theback iscalledbackbonewhich isattached to thebaseoftheskullandextendstheentirelengthattheback.Itisalsoknownasspineorvertebralcolumn.Itismadeupof33smallbonescalledthevertebrae.Th ebackboneprotectsthespinalcord.

(c) Rib cage:Ribs formacage-likestructure in thechest regionofbodycalled theribcage. Itprotectstheheartandlungs.

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4. Bonescannotmoveontheirown.Th eyneedalternatecontractionandrelaxationofmuscles.Whenamusclecontracts,itbecomesshorterandthicker,thusmovingthebonetowhichitisattached.Whenitrelaxes,themusclebecomeslargerandthinner,againmovingthebone.Forexample:armmoveswiththehelpofpairofmusclescalledbicepsandtriceps.

5. Movement in snakes: Snakes are limbless.Th ey use theirmuscles tomove and scales to reducefriction.Th eyalsohaveflexiblebackbonewithhundredsof small sizedvertebraewhichhelp intheirmovement.Th esnake’sbodymovessuchthatinthebodycurvesandmakesloopstopushitforward.

Movement in fi shes:Fisheshavestreamlinedbodywhichhelpthemtocutdowntheresistancefromwater.Th eabilitytomovecomesfromthefinsandthecoordinationbetweenthemusclesaroundtheskeletonoffishanditsfins.Th eyalsohaveflexiblebackbonewhichhelpstheminswimming.Th etailfinhelpsthebodytobendoneithersidealternativelyandtopushitselfforward.Besidesthattheyalsohaveairbladderthathelpsthemtomoveupanddowninwater.

D. Jointbetweentheneckandheadisthepivotjoint.

Jointinthehipisthecalledball-and-socketjoint.

Jointinthekneeishingejoint.E. 1. Underwaterdiverswearflippersasithelpthemtomoveeasilyunderwater. 2. Ifourbackbonewasmadeupofsinglelargebonethenwewouldnothavebeenabletobend.Our

skeletonsystemwouldhavebecomestiff. 3. Wristhasglidingjointthatallowsthebonestoglideovereachotherandfacilitatesmovementinall

directions. 4. Somejointsareimmovableastheyprovideprotection.Forexample:Skull


Worksheet 1 1. Skull—Ithasonlyonemoveablebone,i.e.,lowerjaw,RibCage—Protectsheartandlungs, Backbone—Madeupofmanysmallbones 2. (a) Hingejoint (b) Ball-and-socketjoint (c) Glidingjoint 3. Upstroke movement:Movementofwingsinupwardsandbackwardsdirections. Downstroke movement:Movementofwingsindownwardsandforwardsdirections.

Worksheet 2

1. (a) Snailandearthworm (b) Humansandlions (c) Snailsandcockroaches

(d) Fishandhumans

2. (a) Hingejoint (b) Hingejoint (c) Ball-and-socketjoint

(d) Glidingjoint

3. Birds—Hollowandlightbones Snakes—Limblessvertebrates Snails—Haveanexoskeleton Fishes—StreamlinedBody Earthworms—Segmentedbody

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Chapter 10Habitat and Adaptations

Specific Learning Objectives Aft er the completion of the chapter, students will be able to: • Listdifferenttypesofhabitatsalongwithexamplesoffeworganismsfoundinthesehabitats. • Learnwhysomeorganismsarefoundinaparticulartypeofenvironmentonly. • Knowdifferentadaptationsfoundinorganisms. • Appreciatetheimportanceoftheseadaptations. • Learntheimportanceofhabitattoanorganism.

Materials Required

Teaching Aids:Th eteachingaidsthatcanbeusedinthischapterarespecimensofsomeplantslikeCactus,Hydrilla,Pineleavesandlotusstem.

Warm UpStudentshavealreadystudiedaboutsomeoftheadaptationspresentincamel,intheirpreviousclasses.Th eyarealsofamiliarwithdifferentpartsofaplant.IntroductiontothischaptercanbestartedbyaskingthestudentstocompletetheexercisegiveninWarmupsection.Studentscaneasilyidentifysomeofthesehabitats,thoughtheyarenotfamiliarwiththetermhabitat,butcansuggestthenameoffeworganismsfoundattheseplaces.

Concept Explanation • Habitat and its types:Tounderstandthechapter,thestudentsshouldfirstbemadefamiliar

withtheterm‘Habitat’.Th eyshouldbeexplainedthemeaningofthistermandthefactorsaffectingthehabitatofaplace.Th eyshouldbetoldaboutthedifferencebetweenthetermhabitatandtheenvironment.Differenttypesofhabitatshouldbelistedtothemalongwithexamplesfrombothfloraandfaunaofthathabitat.Differentabioticfactorsofeachhabitatshouldbecovered.

• Adaptations:Th etermshouldbeexplainedtothemalongwiththewaysinwhichananimalcanshowadaptations.

• Desert: Specimen of cactusmight be used to explain the students the adaptive featuresofdesertplants.Rootsofapottedcactuscanalsobeshownto themafteruprooting theplantforbetterunderstanding.Studentsarefamiliarwithsomeoftheadaptivefeaturesofcamel,soclasscanbemadeinterestingbyaskingthestudentswhattheyalreadyknowandthenadding information fromyourside.Th iswill let the informationflowasa twowayinteraction.

• Polar Regions: Different adaptive features of cold regions should be explained to thestudents.Th eimportanceoftheseadaptivefeaturestotheorganismshouldbeexplainedtothestudents.Th echapterincludesdifferentadaptivefeaturesofdifferentanimals,whichwillgiveavarietytothechapterandawideknowledgetotheclass.

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• Grasslands:Studentsshouldbegivenacomparativeaccountoftheadaptivefeaturesofdeerandlionforbetterunderstanding.

• Forests:Differentadaptivefeaturesoforganismsinthreedifferenttypesofforestsshouldbeexplainedtotheclass.Laterthestudentsshouldbeaskedtocomparetheadaptivefeaturesofthethreetypesofforeststhemselvesanddiscussthemintheclass.Termslike:driptipsandcamouflagearenewtothestudentsandshouldbeexplainedtothem.

• Aquatic habitat:SpecimensohHydrillaandanyfloatingplantcanbeusedtoexplainthetopicwithacomparativeaccountbetweenthetwo.Thiswillhelpin‘Learningbyseeing’andwillhelptoimparttheknowledgeinabetterway.Explaintothemthedifferentadaptivefeaturespresentinafishandotheraquaticanimalsalongwiththeimportanceofeachadaptation.

Reinforce • Questions given under the ‘Values’ section and ‘HOTS’ section of the chapter will help

indevelopingThinking skillsamongthem.The ‘Teacher’s tip’givenonpage116and ‘Lifeskill’onpage119willhelpindeveloping‘Love for nature’amongthem.In-textexerciseandexercisesgivenintheendshouldbediscussedinclassforrecapitulationofthechapter.

Explore • An interestingactivitycanbeconducted in theclass,bydividing theclass into twoequal

groups.Askthememberoffirstteamtonameanyanimalorplantandletthemembersofthesecondteamidentifythehabitatinwhichthatorganismispresent.Letthemnameorganismsapartfromthechapterforbetteranddeepknowledge.ThiswillhelptodevelopTeam work skill, thinking skill and love for scienceinthem.

Theactivities givenunder ‘Let’s speak’ and ‘Project’ canbeused as a school activity (e.g,interhouseactivity).Theexperimentmentionedunderthe‘Innovator’scorner’sectioncanalsobecoveredinclass.

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Worksheet 1 1. Give names of any two organisms that are found in the following habitats.

(a) Marine (b) Polarregions

(i) (i)

(ii) (ii)

(c) Coralregions (d) Deserts

(i) (i)

(ii) (ii)

2. Match the two columns.

COLUMN A COLUMN B

Cactus Flexible,longandhollowstem

Lotus TropicalRainforest

Grasslands Stemperformsthephotosynthesis

Pines Strongandwelldevelopedrootsystem

DripTips Needleshapedleaves

3. Write the advantage of the following adaptive features for the organism. (a) Feathersonthebodyofduckarecoveredwithanoilylayer. (b) Camelshavethickleatherylips. (c) Frogsundergohibernation. (d)Deerhavestrong,flatandbroadteeth.

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Worksheet 2

1. Given below is a picture of a fi sh with some of the body parts marked. Give the signifi cance of marked body parts in the survival of fi sh in an aquatic habitat.

Gills

TailFin

Fins

Scales

StreamlinedBody

2. Tell the habitat in which the following organisms are found.

(a) Kangaroorats

(b) Spruce,pinesandconifers

(c) Hydrilla

(d)Reindeerandpolarbear


(a) Hibernatinganimals (b) Aquaticplants

(i) (i)

(ii) (ii)

(c) Animalsthatshowcamouflage (d) Xerophytes

(i) (i)

(ii) (ii)

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A. 1. (a) Cactusand Opuntia (b)Waterlilyandlotus (c) Polarbeerandpenguin (d) Pinesandferns (e) Mapleandoak (f) Fishandwhales 2.

Column A Column BDryandhotarea DeserthabitatMostlygrassesgrowhereandtalltreesareabsent GrasslandhabitatLowtemperature,harshwindsandrockysurface MountainhabitatClosetopolesandcoveredwithsnow PolarhabitatsDensegrowthoftrees Forest habitat

B. 1. Typesofaquatichabitatsaremarine,freshwaterandcoast. 2. Typesofterrestrialhabitatsaregrassland,desert,polarregion,mountainandforest. 3. Ifanimalsdonotadapt,i.e.,iftheycannotchangetheirbehaviourorstructureaccordingtotheir

surroundings,theycannotsurvive.Forexample:fishlivesinwaterbodiesbutitcannotsurviveonlandbecauseitdoesnotdevelopparticularstructuralmodificationwhichenablesittoliveonland.

4. Some animals undergo a deep sleep throughout the winter.Th is is known as hibernation. Inthisstate,animalhaslowbodytemperature,lowrateofbreathingandlowheartrate.Ithelpsinconservingenergy.Animalslikepolarbear,frogs,goldfish,etc.undergohibernation.

5. Camoufl age:Itisthetechniqueusedbyanimalstoprotectthemselvesfromtheirpredatorsandalsohelpsthemtocatchtheirprey.Forexample:leaftailedgecko,stickinsect,etc.showcamouflage.

6. Adaptationsbypolarbear: (i) Itundergoeshibernationwhichhelpsittoconserveenergy. (ii)Th eyaregoodswimmersandwhileswimming theyclose theirnostrils toavoidcoldwater

fromenteringtheirnose. 7. (a) Habitat:Th eplacewhereanorganismlivesnaturallyiscalledhabitat.

(b) Adaptive features:Th emodificationinstructureorbehaviourofanorganismwhichenablesittoliveinaparticularkindofenvironmentiscalledadaptationandsuchfeaturesarecalledadaptivefeatures.

(c) Drip tips:Someleaveshavespecialtipswhichhelprainwatertoslideofffromtheirsurfaceandprotecttheleavesfromrotting.Suchtipsarecalleddriptips.

(d) Estuary:Th eregionwherearivermeetstheseaiscalledestuary. 8. (a) Intropicalrainforest,rateofrainfallishighanddriptipshelprainwatertoslideofffromthe

surfaceofleavesandprotectthemfromrotting. (b)Th econeshapeoftreeshelpsinslidingdownofthesnowanddoesnotallowsnowtocollect

onthesurfaceoftheleaves. (c) Animalsinmountainregionhavethickfurontheirbodyasitprovideswarmthtothebody. (d) In submerged plants, leaves are finely dissected to withstand with water currents without

gettingdamaged. (e) Dolphins and whales do not have gills to breathe in oxygen.Th ey have lungs.Th ey have

blowholeslocatedontheupperpartoftheirhead.Th eyhavetocometothewatersurfacetobreatheinairthroughtheblowholes.Th isallowsthemtostayunderwaterforalongtime.

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(f) Borealforesttressarefoundinmountainregions.Thesoilofmountainregionsdoesnothavenutrients.Treesintheseregionsavetheirenergybynotsheddingtheirleaves.

9. Coralreefsaretherock-likestructuresmadefromcalciumcarbonatesecretedbycorals.Theyarealsoknownasrainforestsoftheseaandarefoundinaquatichabitat.

C. 1. (a)Predator Prey

Theanimalsthatkillotheranimalsforfoodarecalledpredators.Forexample:lion,tiger,etc.

The animals which are killed by otheranimalsforfoodarecalledprey.Forexample:deer,rabbit,etc.

(b)Adaptation Acclimatisation

Certainfeaturesthathelpanorganismto survive well in its environment iscalledadaptation.

The phenomenon in which an organism adjuststo the changing environment through changesthat occur in it for a short period of time is called acclimatisation.

2. Fisheshavegillstobreatheunderwater.Theirstreamlinedbodyshapereducesresistancetowaterandhelpsineasymovementthroughwater.Thescalesontheirbodyprotectthemandmaketheirmovementeasy.Alsothetailandthefinsoffishhelpthemtomove,changedirectionandmaintainbalanceinwater.

3. Lotusisafloatingplant.Itsleavesarelargeinsizeandhavewaxycoatingthatmakestheirsurfacewaterproofandpreventsthemfromrotting.Thestomataarelocatedontheuppersurfaceoftheleaves.Lotus stem is soft,flexible andhollow from inside. Such stemdoesnot let aplant tobecarriedawaybywatercurrents.Theairspacesinthestemallowwatertoflowthroughthestemwithoutbreakingitandalsoenablethelotustofloatinwater.

4. Adaptationsofdesertplants: (i) Desert plants have spineswhichprotect the plant from excess loss ofwater and also from

grazinganimals. (ii) Stemsaregreenincolourwhichperformphotosynthesis.Stemiscoveredwiththickwaxylayer

topreventthelossofwater. (iii) Rootsindesertplantshaveextensiveroothair.Theserootscangodeepinsidethesoilinsearch

ofwater. Adaptations of mountain plants:

(i) Treesdonotshedtheirleavestosavetheirenergy. (ii) Theleavesareneedleshapedandconeshapeoftreeshelpsinslidingdownofthesnowand

doesnotallowsnowtocollectonthesurfaceoftheleaves. (iii) Plantsgrowsclosetothegroundsothatthesecannotgetuprootedbystringwinds. 5. Adaptationsshownbytropicalforestplants:

(i) Treesaretallanddonotallowenoughsunlighttoreachthebaseoftheforest. (ii) Plantshavebroadleavestoabsorbmaximumsunlight. (iii) Stomataarepresentonbothsidesoftheleaves. (iv) Leaveshavedriptipswhichhelprainwatertoslideofffromthesurfaceofleavesandprotect

themfromrotting.

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Adaptationsshownbytropical forest animals: Animalsuseaspecialmethodcalledcamouflagewhichprotectsthemfromtheirpredatorsandalso

helpsthemtocatchtheirprey.Forexample:leaftailedgecko,stickinsect,etc.,showcamouflage. Adaptationsshownbytemperateforestplants:

(i) Plantshavethin,broadleavesthatallowthemtocapturesunlighteasilyformakingfood. (ii) Treesshedtheirleavesduringwinterasthebroadleavesarenotabletobearthefreeingwinter. Adaptationsshownbytemperateforestanimals: Manyanimalshibernateormigrate towarmerregionsduringwinter.Animalscollectandstore

foodforwinter,whenfoodbecomescarce.D.

Two-toed feet withthick leathery pads

Ears are covered with hairs,even from inside to protectears from sand or dust Long eyelashes

and bushyeyebrows

Thick leathery lips help eating the thorny desert plant

Fat-filledhump

E. 1. Broadleavesencouragemorelossofwaterfromthesurfaceofleaveswhichisnotsuitedforthedesertregionastheavailabilityofwaterisverylowinthatregion.

2. In submerged plants, root system is poorly developed but its leaves are finely dissectedwhichwithstandwithwatercurrentswithoutgettingdamaged.

3. Ananimalcanbebothpredatorandaprey.Forexample:asnakepreysonrabbitandaneaglepreysonsnake.

4. Hibernatinganimalseatalotbeforegoingintohibernationastheyaccumulatefatswhichserveastheenergyproviderintheharshconditionsofpolarregion.

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Answers to WorksheetsWorksheet 1 1. (a) Whaleandshark (b)Reindeerandmuskox (c) Seaanemonesandoctopus (d)Camelandrat 2. Cactus—Stemperformsthephotosynthesis Lotus—Flexible,longandhollowstem Grasslands—Strongandwell-developedrootsystem Pines—Needleshapedleaves DripTips—Tropicalrainforest 3. (a) Tomaketheirbodywaterproof (b) Sothattheycaneatthornydesertplantswithoutfeelingthepain. (c) Tosurviveandtoconserveenergyinlowtemperatures (d) TochewthehardgrassWorksheet 2 1. Scales:Protectthemandmaketheirmovementeasy Tail fi n:Helpthemtomove,changedirectionandmaintainbalanceinwater Gills:Tobreatheunderwater Streamlined body:Reducesresistancetowaterandhelpsineasymovementinwater Fin:helpsthemtomove 2. (a) Desert (b) Polarandmountainregion (c) Aquatic (d) Polarregion 3. (a) Hedgehogsandwasps (b) LotusandHydrilla (c) Leaf-tailedgeckoandstickinsects (d) Opuntia and cactus

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Answers to Summative Assessment 1

A. 1. (d) 2. (c) 3. (c) 4. (c) 5. (b)

B. 1. acclimatisation 2. chemical 3. venusflytrap 4. driptips 5. evaporation

C. 1. Ruminants 2. Marasmus 3. Camouflage 4. Species 5. Chitin 6. Venation 7. Estuary

D. 1. (a) Retting:Th eprocessofseparatingjutefibresfromjuteplantsbyrottingofstemsofjuteplantsinwatertoremovestickysubstanceiscalledretting.

(b) Solubility:Th epropertyofvarioussubstancestodissolveinwateriscalledsolubility.Examplesofsolublesubstancesaresugar,salt,alcohol,etc.

(c) Cold-blooded animals:Animalswhosebody temperaturechangeswith temperatureof theirsurroundingsarecalledcold-bloodedanimals.Forexample:insects,reptiles,etc.

2. Tearing of paper does not create a new substance as no change in the molecular structure isobserved,soitisaphysicalchange.Butburningofpaperresultsintheformationofashwhichisanewsubstance,soitisachemicalchange.

3. Organismsadapttotheirhabitatbythefollowingways: (i) Changesinbodystructure (ii) Changesinbehaviour (iii) Changesinlocation 4. Featuresofbirdthathelpthemtoflyareasfollows.

(i) Hollowandlightbonesreducetheirbodyweight. (ii) Breastbonesofbirdsarestrongandlargethatprovideasurfaceforattachmentofflightmuscles

whichenablesthemtofly. (iii) Streamlinedbodyalsohelpstoreducetheresistanceofairwhileflying. (iv) Powerfulchestmuscleshelpthemflaptheirwingsduringflight. 5. (a) Hip:Ball-and-socketjoint

(b) Finger:Hingejoint (c) Ankle:Glidingjoint

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E. 1. Bonescannotmoveontheirown.Theyneedalternatecontractionandrelaxationofmuscles.Whenamusclecontracts,itbecomesshorterandthicker,thusmovingthebonetowhichitisattached.Whenitrelaxes,themusclebecomeslargerandthinner,againmovingthebone.Armmoveswiththehelpofpairofmusclescalledbicepsandtriceps.

2. Modificationsinleaves: (i) In some plants like pea, leaves are modified into a shape of tendrils which are slender,

spring-likestructuresandhelpsplanttoattachthemselvestosupport. (ii) Insomeplants,thepetiolerendoftheleafgivesrisetothenewplant. (iii) Inplantslikecactus,leavesarereducedtospinestopreventthelossofwaterbytranspiration. (iv) Insomeplants,leafsaremodifiedintospecialshapesforcatchinginsectstofulfilthenitrogen

requirementoftheplant. Modificationinstems:

(i) Stemsofcertainplantscanbeusedtogrownewplants.Forexample:roseandjasmine. (ii) Insomeplants,stembecomesfleshytostorewater.Forexample:cactus. (iii) Somemodifiedstemsthatgrowundergroundandstorefood.Forexample:ginger. (iv) Insomeplants,stemismodifiedintosharp,woodyandpointedstructures.Forexample:rose. (v) Stemsofclimberssuchasgrapevine,aremodifiedtoformthread-likeandcoiledstructurethat

providesupporttotheplant. 3. (a)

Reversible change Irreversible changeThe change which can be reversed is calledreversiblechange.Forexample:inflationanddeflationofballoon

The changewhich cannot be reversed iscalledirreversiblechange.Forexample:Cuttingoffruits

(b)Conductor Insulators

Materialsthatallowheatandelectricitytopassthroughthemarecalledconductors.Forexample:Copper,iron,etc.

Materials that do not allow heat andelectricitytopassthroughthemarecalledinsulators.Forexample:plastic,glass,etc.

4. Processing of jute fibres: Jutestemhasa thickbarkandcontainsfibres inside it. Jutefibresarenaturallygluedtogetherbystickysubstance.Thisstickysubstanceisremovedbyaprocesscalledrettinginwhichjutestalksarecuttothegroundandtiedintobundles.Thesearethensoakedintowaterforabout20days.Afterretting,thefibresareseparatedfromthestem,washed,driedandtiedintobundles.Inthiswayjutefibresareseparatedfromjutestem

Processing of cotton fibres:Stepsinvolvedareasfollows. (i) Ginning:Seedsareremovedfromcottonfibresbycombing.Inthisprocess,strongaircurrents

areused. (ii) Spinning:Inthisprocess,threadoryarnsaremadefromcottonfibre.Itisdonewiththehelp

ofahandspindleoraspinningwheel. (iii) Weaving or knitting:Weaving is theoldestmethodofusingyarn tomake fabric inwhich

threadsarewovenintoclothesonaloom.Theloomsareeitherhandoperatedcalledhandloomormachineoperatedcalledpowerloom.Thepattern inwhichtwodistinctsetsofyarnsareinterlacedatrightanglestoformafabriciscalledaweave.

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While inknitting,asingleyarnisusedtomakeafabric.Thiscanbedoneeitherusingknittingneedlesormachines.Aseriesof interlocksor loopsaremade in theyarn to forma fabric.Theconsecutiverowsofloopsinaknittedfabricarecalledstitches.

5. Adaptationsshownbyplantsinterrestrialhabitatareasfollows. (i) Indesert area, plants have spines and thick stem tominimise the loss ofwater.Theyhave

extensiveroothairwhichcangodeepinthesoiltoabsorbwater. (ii) Inborealforest,treeshaveconeshapeandneedle-shapedleaveswhicharenevershed.Plants

growsclosertothegroundsothatthesecannotgetuprootedbystrongwinds. (iii) Ingrasslandhabitats,plantshaveflexiblestem,narrowleavesandstrongrootsystemwhichfix

theplanttothesoil. (iv) Intropicalrainforest,treesareverytallandplantsatthebaselevelhavebroadleavestoabsorb

moresunlight. (v) Intemperateforest,treeshavethinandbroadleavestocapturesunlight.Theyshedtheirleaves

duringwinter. Adaptationsshownbyplantsinaquatichabitatareasfollows.

(i) Rootsarereducedinsizeandtheirmainfunctionistoholdtheplantinitsplace.Roothairareabsent.

(ii) Stemofaquaticplantsissoft,flexibleandhollowfrominsidewhichdoesnotletaplanttobecarriedawaybywatercurrents.

(iii) Leavesarelargeinsizeandhavewaxycoatingthatmaketheirsurfacewaterproofandpreventsthemfromrotting.Thestomataislocatedontheuppersurfaceofleaves.

(iv) In caseof submergedplants, leaves arefinelydissected and ribbon-like towithstandwatercurrentswithoutgettingdamaged.

F. 1. Animalsundergodeepsleeptoconservetheirenergy. 2. Polarbear,wasps,hedgehogs,groundsquirrels,fat-tailedlemursandgoldfishundergowintersleep. 3. Hibernation may last for several days, weeks or months depending on the animals and the

temperatureofthesurroundings.G. 1. RahulneedsmoreenergyascomparedtoSureshasRahuldoesmorephysicalworkthanSuresh.So,

Rahulneedsmorecarbohydratesinhisdiet. 2. Inwinter,pipescontractduetowhichtheycrack.

75

Model Test Paper 1 100 marks

A. Tick () the correct option. 6 × 1 = 6 1. Whichofthefollowinghappensduetothedeficiencyofwater?

(a) Protein (b) Vitamin (c) Water (d) Fat

2. Whichofthefollowingfibresmeltsonburning?

(a) Cotton (b) Jute (c) Wool (d) Rayon

3. Whatmakethegraphitedifferentfromothernon-metals?

(a) State (b) Lustre (c) Solubility (d) Flotation

4. Whichofthefollowingmethodsisusedtoseparatesandfromwater?

(a) Evaporation (b) Condensation (c) Filtration (d) Sieving

5. Whichofthefollowingisawarm-bloodedanimal?

(a) Fish (b) Insects (c) Mammals (d) Reptiles

6. Whichofthefollowingplantshaveribbon-likeleaves?

(a) Lotus (b) Hydrilla (c) Waterlily (d) Duckweed

B. Fill in the blanks. 8 × 1 = 8 1. Inwheat,_____________venationisfound.

2. Th eexoskeletonofcockroachesismadeupof________________.

3. Th eanimalsthathuntsandkillsotheranimalsarecalled_______________.

4. Peelingofanappleisa___________change.

5. Asolutedissolves______________whenthesolutionisstirred.

6. Deficiencyofproteinsalongwithcarbohydratesresultsin_________________.

7. Plantspresentindesertsarecalled____________________.

8. X-rayswerediscoveredbythe_____________________________.

C. Defi ne the following. 8 × 2 =16 1. Parasites 2. Rettingofjute 3. Flotation

4. Desalination 5. Sensitivity 6. Cartilage

7. Driptips 8. Liquidskeletalsystem

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D. Answer the following briefl y. 10 × 3 =30 1. Writeany2adaptationseachofdolphinandsquid.

2. Howdocockroachesmove?

3. Writeany3functionsofleaf.

4. Whatisthedifferencebetweencold-bloodedandwarm-bloodedanimals?

5. Explaintheconceptofexpansioninsolids,liquidsandgases.

6. Explainthepropertiesofcopperbeingametal.

7. Howisjutecultivated?

8. Whataresolubleandinsolubleroughage?Giveexamplesalso.

9. Whatareglidingandhingejoints?Explainwiththehelpofexamples.

10. Howdoesaleafdothefollowingfunctions?

(a)Supportingtheplant (b)Reducingtranspiration(c)Protectingtheplant

E. Answer the following in detail. 5 × 5 = 25 1. Whatispollination?Explainitstypeswiththehelpofadiagram.

2. Whatarebioticandabioticcomponents?Explaintheinteractionbetweenthesetwo.

3. How common salt is separated from salt solution?Explain itwith the help of anexperiment.

4. Whataretheadaptationsofanimalsingrasslandhabitat?

5. Explainthemovementinbirds.

F. Look at the given picture and answer the following questions. 1. 2+2+3=7

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(a) Whattypeofchangeisshownbyburningofcoal?

(b)Whattypeofchangeisshownbyburningofcandle?

(c) Howdothegivenpicturesdifferfromeachother?

2. 2+2+4=8

Wire gauzeSalt solution

Stand

Burner

Beaker

(a) Whatisbeingdepictedinthegivenpictures?

(b) Howarethesepicturesrelated?

(c) Giveanexampleinwhichbothprocessescanbeshown.

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Chapter 11Motion and Measurement

Specific Learning Objectives Aft er the completion of the chapter, students will be able to: • Learnabouthowmeansoftransportdevelopedfromancienttomoderndaytimes. • Differentiatebetweenmotionandrest. • Understanddifferenttypesofmotion. • TelltheSIunitsofdifferentquantities. • Representmeasurementsinpropermanner. • Identifythetypeofmotionshownbyamovingobject. • Convertoneunitofmeasurementoflengthintoanother.

Warm UpToproceedwellinthischapterthestudentsshouldhaveapreviousknowledgeofmultiplicationanddivision.Th eclasscanbestartedbyperformingtheactivitygivenundertheWarmupsectionofpage125.Th estudentsshoulddothisactivityindividuallytoobtaindifferentanswers.

Concept Explanation • History of transport:Th is is an easy topic to start with.Th e studentsmight be knowing

somethingaboutthedevelopmentoftransportfromancienttopresentday. • Types of motion:Differenttypesofmotionswiththeirsubtypesshouldbediscussedinclass.

Th eseshouldbeexplainedtothestudentswiththehelpofmanyexamples.Th esemotionsarenewforthestudentstounderstandsoalotofpracticeshouldbegiventothestudentswiththehelpofexamplessothattheycanidentifythetypeofmotionshownbyaparticularmovingobject.Th eyshouldalsobeexplainedthataparticularobjectcanevenshowmorethanonemotionatatime.

• Measurement:Differentnon-standardunitsshouldbeexplainedtotheunits.Th estudentsshouldalsobeexplainedthestandardunitsofmeasurementandalsoabouttheSIsystemofunits.Th eimportanceofstandardunitsofmeasurementovernonstandardonesshouldbecoveredintheclass.

• Conversions: Lot of practice should be given to the students on quick conversion of oneunit of length to another.Conversion at both decreasing and increasing levels should betaughtintheclass.Th iswillhelpthemalotintheirday-to-dayactivities.Th iswillhelpinthedevelopmentoftheskillof‘learningbydoing’.

• Measurement of length:Properuseof a ruler andadivider shouldbe taught in the class.Th istopicshouldbegivenasapracticalapproach,i.e.explainingthisbyusingarulerandadivider.Alsothemeasurementofacurvedlineusingathreadcanbeshowntothestudentintheclass.

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Reinforce • Manyexamplesofdifferenttypesofmotioncanbegiventotheclassandstudentsmightbe

askedtoidentifythetypeofmotion.Definitionsofthesedifferenttypesofmotioncanberepeatedfromthe‘Worddrop’section.Theexercisesgiveninbetweenthetextandalsoattheendofthechaptershouldbediscussedintheclass.

Explore • Studentscanbegivena setofquestionnaireonconversion fromoneunit toanotherand

canbeaskedtosolvethisindividually.Thiscanevenserveasaninter-disciplinaryformativeassessmentactivity(ScienceandMaths).Studentscanbeaskedtoperformtheactivitygivenunderthe‘Let’sspeak’and‘Project’sections.Theresultsoftheseactivitiesmightbediscussedintheclassifthetimepermits.

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Worksheet 1

1. Identify the type of motion in the following.

(a) Openingadrawer.

(b) Toandfromotionofapendulumofaclock.

(c) Amovingdrillmachine.

(d) Earthrotatingonitsaxis.

(e) Acarmovingonaroad.

2. Complete the following.

(a) 1.1km= m

(b) 2.1cm= dm

(c) 1m= cm

3. Convert the following.

(a) 98.065cmtom

(b) 26,950mtokm

(c) 950cmtom

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Worksheet 2

1. Complete the following table.

Quantity SI Unit

Length

Second(s)Kilogram(kg)

Temperature

2. Give two examples for the following types of motions.

(a) Non-periodicmotion:

(b) Rotationalmotion:

(c) Circularmotion:

3. Which types of motions can be seen in the following?

(a) Motionofacarontheroad

(b) Amovingdrillmachine

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A. 1. (a) non-standard (b) Internationalsystemofunits (d)metre(m) (e) circular,periodic 2. (a) Whenabodymovesinastraightline,itissaidtobeinarectilinearmotion.

(b)Th eSIunitforlengthismetre. (c)Wealwaysexpressourmeasurementinnon-standardunits. (d) Inrotationalmotion,allthepartsofthemovingobjectdonotcovertheequaldistance. (e) Cubitisanon-standardunitoflength.

B. 1. Intheancienttime,peopleusedtowalkonfoottocoverdistanceastherewerenomeansoftransport.Tocoverlargedistances,theyusedtorideonanimals.Totravelacrossrivers,raftsandboatsmadefromwood,wereused.Inventionofwheelbroughtaboutachangeinthemodeoftransportandin1781,inventionofsteamenginebyJamesWatt,broughttherevolutionintransport.Inthemoderntimes,transportsystemincludesaeroplanes,highspeedtrains,motorisedboatsandshipswhichmadethetransportationeasyandquick.

2. (a) Motion:Whenanobjectchangesitspositionwithtimewithrespecttoanotherobject,itissaidtobeinmotion.

(b) SI units: Th efixedunitofmeasurementusedbyeveryonetogetauniformresultiscalledSIunit.

(c) Measurement:Th ecomparisonofanunknownquantitywithaknownfixedquantityof thesamekindiscalledmeasurement.

3. Handsofaclockshowbothperiodicandcircularmotionsatthesametime. 4. (a) 20mtocm 1m=100cm 20m=100×20=2000cm (b) 1000kmtom 1km=1000m 1000km=1000×1000=1000000m (c) 10mtodm 1m=10dm 10m=10×10=100dm (d) 30cmtomm 1cm=10mm 30cm=10×30=300mm 5. Whenobjectdoesnotchangeitspositionwithtime,itissaidtobeatrest. 6. Initialpoint-3.5cm Finalpoint-22.5cm Actuallengthoflinesegment=Finalpoint–Initialpoint =22.5cm–3.5cm =19cm

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7.

Periodicmotion Non-periodicmotionThe motion that is repeated after a regularintervaloftimeiscalledperiodicmotion.Forexample:Motionofpendulumofclock

Themotion that is repetitive but occurs at aregularintervaloftimeiscallednon-periodicmotion.Forexample:Childrenplayinginapark

8. (a) Arrowreleasedfrombow (b) Rotationofearth (c) Handsofaclock (d) Birdsflyinginthesky (e)Motionofbladesofafan

C. 1. Typesofmotion: (i) Translatory motion:Whenallthepartsofanobjectmovethesamedistanceinanintervalof

time,thenmotioniscalledtranslatorymotion.Itisoftwotypes: (a) Rectilinear motion: When an object moves in a straight line, it is said to be in the

rectilinearmotion.Forexample:Openingofadrawerandapplefallingfromatree. (b) Circular motion:Whenanobjectmoves ina circularmanner, it is said tobe circular

motion.Forexample:Handsofclockandmovingwheelofabicycle. (ii) Periodic motion: Themotionthatisrepeatedafteraregularintervaloftimeiscalledperiodic

motion.Forexample:MotionofthependulumofclockandmotionofEartharoundthesun. (iii) Non-periodic motion:Themotionthatisrepetitivebutoccursataregularintervaloftimeis

callednon-periodicmotion.Forexample:Childrenplayinginaparkandbirdsflyinginthesky.

(iv) Rotational motion:Whenanobjectmovesaroundanaxisandallofitspartsdonotcoverthesamedistanceinagiventimeiscalledrotationalmotion.Forexample:motionofbladesofwindmillandrotationofearthonitsaxis.

2. (i) Cubit:Itisthedistancefromthetipofthemiddlefingertotheelbow. (ii)Handspan:Itisthelengthofthestretchedouthand.

(iii) Footstep:Itisthelengthoftheonefootstep. 3. Benefitsofhavingacommonsystemofmeasurementisthatitgivesunitsthataremoreaccurate

andreliableandcanbeusedbyeveryonetogetthesameresults.Alsotheydonotvaryfrompersontopersonandplacetoplace.

4. Stepstobekeptinmindwhileusingarulertomeasurelength: (i) Objectshouldbeplacedsuchthatthe0-pointoftherulercoincideswiththestartingpointof

theobject. (ii)Therulershouldbeplacedexactlyalongthelengthoftheobjectwhichistobemeasured. (iii) Donotusetheruler,theedgesofwhicharebrokenormarkinghavebeenerasedduetooveruse. (iv) Youreyesshouldbeexactlyinthefrontofthereadingwhilenotingtheresult.

D. (a) Rectilinearmotion (b) Non-periodicmotion (c) Circularmotion

E. 1. TheEarthisrotatingandrevolvingaroundthesunconstantly.Sotrees,buildings,humans,animals,etc.,alsomovealongwiththeEarth.Thus,wecansaythateverythingisinconstantmotion.

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2. Tomeasurethethicknessofonerupeecoin,wefirsttake15one-rupeecoinandthelengthofstackismeasuredbyusingaruler.

Letthelengthofstackof15one-rupeecoin=x Now,thethicknessof1one-rupeecoin=x/15 3. Th eunittomeasurethedistancescoveredbyanaeroplaneandshipisnauticalmile. 4. Urvashiboughtonly4mofthecloththatmeans400cmoftheclothbutsheneeded500cmofthe

cloth.Shewouldnotbeabletogetheroutfitstitched.


Worksheet 1

1. (a) Rectilinearmotion (b) Periodicmotion (c) Rectilinearandrotationalmotion

(d) Rectilinearandcircularmotion

2. (a)1100m (b) 0.21dm (d) 100cm

3. (a)1cm=1/100m

So,98.065cm=98.065/100=0.98065m

(b) 1m=1/1000km

So,26950m=26950/1000=26.950km

(c)1cm=1/100m

So,950cm=950/100=9.50m

Worksheet 2

1. Metre(m),Time,MassandKelvin(K)

2. (a)Acarmovingonaroadandabirdflyinginthesky

(b)Rotationofearthonitsaxisandmotionofthebladesofwindmill

(c)Handsofaclockandamovingwheelofamovingcar

3. (a)Rectilinearandcircularmotion

(b)Rectilinearandrotationalmotion

85

Chapter-12Light, Shadows and Refl ection

Specific Learning Objectives Aft er the completion of the chapter, students will be able to: • Tellsomepropertiesoflight. • Enumerate differences between luminous and non-luminous objects and uniform and

diffusedreflection. • Classifydifferentobjectsastransparent,translucentandopaque. • Demonstratedifferentshapesthatcreatesameshadows. • Performsimpleexperimentstoshowsomepropertiesoflight. • Listcharacteristicsofashadow.

Materials RequiredTeaching Aids:Th edifferentteachingaidsthatcanbeusedinthechapteraretheonerequiredtoperformExperiments1-3andtheactivitygivenunderthe‘Innovator’scorner’.

Warm UpStudentshaveknowledgeofclassifyingobjectsonthebasisoftransparencyastheyhavealreadydonethisintheirpreviouschapters.Th eycanevenperformtheactivitygivenunderthe‘Warmup’section.Th iswillbeagoodexercisetostartbeginthechapter.

Concept Explanation • Luminous and non-luminous objects:Studentsshouldbeexplainedthemeaningofthesetwo

termsalongwiththeexamples. • Transparency: Students are already familiar with the terms transparent, translucent and

opaqueobjects.Th eycanalsogiveexamplesofsuchobjects.Th istopiccanthusbecoveredasastudentguidedclasswheresomestudentscanexplainthetopictootherstudents.

• Rectilinear propagation of light:Th is can be explained to the students with the help ofExperiment1tofacilitate‘Learning by seeing’.Th econceptofrayandbeamshouldalsobecoveredintheclass.

• Shadows: Students must be familiar with the term shadow, but they cannot list thecharacteristicsofashadow.Th eteachershouldexplainthesetothestudents.Forthisobjectsofdifferentshapecanbeused(assuggestedinActivity3ofpage140).Atdifferentpointsduring theactivity, the teachercanchange thedistancebetween the light sourceand theobjectorbetween theobjectand thescreenandcanask thestudents tonotedowntheirobservations.

• Refl ection:Activity4orExperiment2willhelpinexplainingtheconceptofreflectiontothestudents.Studentsmusthaveobservedsuchphenomenonintheirdailylives,sothejoboftheteacheristolinktheirday-to-dayobservationtotheirunderstanding.Th iswillhelpinthedevelopmentofTh inking Skills and scientifi c aptitude amongthem.

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• Pinhole camera:Modelofthiscameracanbeusedtoexplainapinholecameratothestudents.Thiscameraisveryeasytoprepareandthemodelofthiscameracanbegivenasanactivitytotheclasseitherindividuallyorasateamwork.

Reinforce • The questionsmentioned under ‘Values’, ‘Life skills’ and ‘HOTS’ will help in developing

Thinking and reasoning skillsamongthestudents.Theseshouldbediscussedintheclass.Theintextandbackquestionswillhelpinrecapitulationofthechapter.

Explore • Studentscanfurthergainadeepinsightofthetopicbyperformingtheactivitiesmentioned

under‘Teacher’stip’givenonpage141andthe‘Innovator’scorner’givenonpage146.

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Worksheet 1 1. Complete the given table:

Object Luminosity (luminous/ Non-Luminous)(a)Lightedcandle(b)Redhotiron(c)Wax(d)Stars(e)Lamp(f)Lightedbulb(g)Plastics(h)Glowworms(i)Switches(j)Earth(k)Firefly(l)Torch

2. Write the requirements for the formation of a shadow.

3. Identify which picture represents the uniform refl ection and which one represents the diff used refl ection.

__________________________ __________________________

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Worksheet 2 1. Complete the given table.

Object Transparency ( Transparent/ Translucent/ Opaque)

(a)Clearwater

(b)Air

(c)Glass

(d)CellophaneSheet

(e)Tracingpaper

(f)Mirror

(g)Moon

(h)Sun

(i)WireGauze

(j)Frostedglass

2. Tick () the one/s that is/are a feature of a shadow.

(a) Itcouldbeofdifferentcoloursdependingontheobject.

(b) Itgivesanexactideaabouttheshapeandsizeoftheobject.

(c) Th eshapeoftheshadowdependsontheshapeoftheobject.

(d)Th eshapeoftheshadowdependsonthepositionofthelightsourcealso. (e) Th esizeoftheshadowdecreasesifwedecreasethedistancebetweenthe objectandthelightsource.

3. Tick () the principle behind the working of a pinhole camera.

(a) Rectilinearpropagationoflight

(b) Splittingoflight

(c) ShadowFormation

(d)Reflectionoflight

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A. 1. (a)True (b) False (c) True (d) False (e) True 2. (a)natural,man-made (b) pinhole (c) shadow (d) opaque,translucent (e) star,tubelightB. 1. Th erectilinearpropagationoflightcanbeexplainedbyraysandbeamoflight.Lightcannotbend

orchangeitsdirectionifthereisanobstruction.Forexample:Incinemahalls,lightcomefromaprojectorandtravelsinastraightline.

2.Ray Beam of light

Itisrepresentedbyalinewithanarrowheaddrawntoshowthedirectionofpropagationofthelight.

Itisbroaderandisacollectionofseveralparallel rays moving in an organisedmanner.

3. Ifwe increase thedistancebetween theobject and the light source, the sizeof the shadowwilldecrease.

4. Suchobjectsreflectthelightoftheluminousobjectsandthusappeartobevisible.Forexample:Moonisanon-luminousobjectwhichreflectsthelightofsunandthus,visibleatnight.

5. Sourceofenergyinstars:Fusionreaction Sourceofenergyintorch:chemicalreactiontakesplaceinthebatteries 6. (a) Luminous objects: Th eobjectsthathavelightoftheirownarecalledluminousobjects.For

example:stars,tubelight,sun,etc. (b) Refl ection of light:Th ephenomenonofchangeinthedirectionoflightwhenitstrikesthe

bodyorasurfaceiscalledreflectionoflight.C. 1. Tomakeasimplepinholecamera,werequiremediumsizecardboardwithonesideopen,tracing

paper,adhesivetape,apairofscissors,blackpaintandrubberbands.Nowfollowthegivensteps: (i) Paintthecardboardinblackfromallthesides. (ii)Makeasmallholewithaneedleonthesideoftheboxthatisoppositetotheopenside. (iii) Covertheopensideoftheboxwithatracingpaperusingadhesivetapesandrubberbands.

Th issideformsthescreenofthecamera. (iv) Pinholecameraisreadytouse. 2.

Transparent object Opaque object(i) Th eobjectthatallowslighttopassthroughit.

(ii) Itdoesnotformshadowwhenlightfallsonit.

(iii)Forexample:Plainglass,clearplasticsheet,etc.

(i) Th e object that does not allow thelighttopassthroughit.

(ii) Itformsshadowwhenlightfallsonit.

(iii)For example: Book, ball, cardboard,etc.

3. (a) To show the rectilinearmotion of light, we need three same size of rectangular pieces ofcardboard,table,woodensupports,ironnailsandalightedcandle.Nowthefollowingstepsaretaken:

(i) Lightedcandlewastakenandfixeditonthetable. (ii) Smallholewasmadeatthecentreofeachofthethreecardboardsandmadesurethatthe

holeswereatthesamelevelinthethreecardboards.

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(iii) Cardboardswerearrangedonthewoodensupportsinsuchawaythatthethreeholesandthecandlewereinastraightlineandthecandleflamewasvisiblethroughthethreeholes.

(iv) Nowonslightlydisplacingofanyofthecardboard,weobservethatflameisnotvisible. Th isprovesthatlighttravelsinastraightline.

(b) Toshowthereflectionoflight,werequirethermocolsheet,small-sizedplanemirror,comb,whitepaperandatorch.Nowthefollowingstepsaretobetaken:

(i) Mirrorisfixedononesideofthethermocolsheetandcombontheothersideofthesheetinsuchawaythatreflectingsurfaceofmirrorfacedthecomb.

(ii) Nowwhitesheetwasspreadbetweencombandthemirror. (iii) Lightfromthetorchwasthrownonthecombsothatitreachedthemirror. (iv) Nowweobserveanet-likepatternofthecomb. Th isisbecausethelightrayspassthroughthecombandstrikethemirrorandafterstrikingthe

mirror,theraysgetreflectedandanet-likepatternisformedonthewhitepapersheet.

D. Clearandinvertedimageofboywillbeobtainedonthescreenbythepinholecamera.E. 1. Sometimesmultipleshadowsofanobjectareobserved.Th isisduetothepresenceofmorethan

onelightsourcewhichwhenfallonobjectfromdifferentanglescancastthedifferentshadows.Alsowhenonelightsourcethrowsthelightontheobjectfromdifferentpositions,multipleshadowsareformed.

2. Opaquewhitesheetcanbeturnedintotranslucentbyrubbingsomeoilonit. 3. Atnoon, thedistancebetween the sun and theobject is less, so long shadowwill form. In the

morningandeveningtime,thedistancebetweenthesunandtheobjectislarge,sosmallshadowwillform.

Answers to WorksheetsWorksheet 1

1. (a) Luminous (b) Luminous (c) Non-luminous (d) Luminous

(e) Luminous (f) Luminous (g) Non-luminous (h) Luminous

(i) Non-luminous (j) Non-luminous (k) Luminous (l) Luminous

2. Asourceoflight,anopaqueobjectandascreenorsurfacebehindtheobject

3. (a) Uniformreflection (b) Diffusedreflection

Worksheet 2

1. (a) Transparent (b) Transparent (c) Transparent (d) Transparent

(e) Translucent (f) Opaque (g) Opaque (h) Opaque

(i) Opaque (j) Translucent

2. (b),(c)and(d)

3. Rectilinearpropagationoflight

91

Chapter 13Fun With Magnets

Specific Learning Objectives Aft er the completion of the chapter, students will be able to: • Locatedifferentpolesofamagnet. • Learnaboutthepropertiesofamagnet. • Makeuseofamagneticcompasstofinddirections. • Maketheirowntemporarymagnetandmagneticcompass. • Analysethedifferencebetweenmagneticandnon-magneticmaterialsandapplythisasa

methodofseparationbetweenthem. • Judgedifferentmethodsforproperstorageofmagnets.

Materials RequiredTeaching Aids:Th ischapterincludesalotofexperimentsandactivitiesandthesewillbehelpfulindeveloping skills among the students.Many teaching aids canbeused that are required forcompletingthesevariousexperimentsandactivities.

Warm UpTomaketheclass interesting,theteachercanstartthetopicbyaskingquestionslike:Whataremagnets?Wherearetheyusedinourdailylife?DiscussthemintheclassandthenaskthestudentstocompletetheactivitygivenundertheWarmupsection.Th estoryonthediscoveryofmagnetswillmaketheclassinteresting.

Concept Explanation • Magnets:Magneticandnonmagneticmaterialsandtypesofmagnetsshouldbediscussed

withthestudents.StudentsshouldbeaskedtocompleteActivity1anddiscusstheactivityintheclass.

• Poles of a magnet:Differentshapesofamagnetcanbeusedtoexplainthepolesofamagnetandmanyotherpropertiesrelatedtomagneticpoles,like;amagnetisdipolar,magnetismismaximumatpolesandpropertyofattractionandrepulsion.Polesofdonutshapedmagnet,circularmagnet, horse shoe shapedmagnet can be shown to the students by using theattractionofamagnettowardsironfillingsastheactivity.Earth’smagneticpolesshouldalsobetaughtintheclass.

• Making your own magnet: Experiment 3 should be performed in the class to explainthistopic.Studentsshouldbetoldthatonlyamagneticmaterialcanbeconvertedintoatemporarymagnet.

• Magnetic compass:Amagneticcompassshouldbeshowntothestudentsanditsworkingandconstructionshouldbetaught.Atemporarymagneticcompasscanalsobepreparedintheclass.Sciencefactonmagneticcompass,givenonpage154,canalsobetoldtothestudentsasinformation.

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• Uses and taking care of magnets:Studentsshouldbeexplainedthatmagnetsareusedinmanyfieldsandshouldbestoredproperlysothattheirmagnetismisretainedforalongerperiod.Thetermdemagnetisationshouldbeexplainedtothem.

Reinforce

• Thein-textandthebackexercisequestionswillhelpthestudentstoretaintheknowledgegained.This will help them in better understanding and the answers to these should bediscussedintheclass.Studentscanhavealookatdifferentmagnetsandmagneticcompassontheirownandtheyshouldbegivenachancetousetheminfindingdirectionsandtostudythepropertiesofamagnet.ThiswillhelpindevelopingThinking skills and learning by doing amongthem.

Explore • Theactivity givenunder the ‘Life skill’ section and ‘Innovator’sCorner’ onpage 158will

helpthestudentstogetabetterinsightonthechapter.Thiscanalsobegivenasaformativeassessmentactivitytothem.

93

1. Tick (√) the magnetic materials in the following. (a) Nickel (b) Gold (c) Cobalt (d) Iron (e) Copper (f) Stainlesssteel (g) Plastics

2. Select the one that shows the right method of storing bar magnets.

MAGNETS

KEEPERS

NNN S

SSS N

(a) (b)

3. Write two uses of magnets.

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

Worksheet-1

94

1. Tick () the characteristics of a magnet.

(a)Magneticpolescanbeseparated.

(b)Magnetcanalsoattractanalloyofiron.

(c)Likepolesofamagnetrepeleachother.

(d)Magnetismisequalthroughoutthelengthofabarmagnet.

(e)Afreelysuspendedmagnetalignsinnorth-southdirection.

2. Identify the given device and write one use of this device.

_______________________________________________________________

3. Fill in the blanks to complete the process of preparing a temporary magnet.

(a) Takeanironneedleandkeepitonatable.

(b)Nowtakeabarmagnetand

_______________________________________________________________

(c) Whenyoureachtheotherendoftheneedleliftthemagnetand

_______________________________________________________________

(d)Repeatthisprocessforabout30-40timeswiththesamepoleofthebarmagnet.

(e) Testyourmagnet(needle)by

_______________________________________________________________

(f) Ifitattractstheclipsthenyourneedlehasbecomeatemporarymagnet,otherwise

_______________________________________________________________.

(g) Th eironneedlehasbecomeatemporarymagnet.

Worksheet-2

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A. 1. (a) Earth (b) heated,hammered (c) North,south (d) compass (e) South 2. (a) False (b) False (c) True (d) True (e) False

B. 1. ItisbelievedthatashepherdnamedMagnesdiscoveredthemagnetintheareacalledMagnesiathatliesintheNorthernGreece.Itissaidthatwhileherdinghissheep,themetalendofhisstickgotstucktoalarge,blackcolouredrock.Th isrockwaslaternamedasMagnetiteandissaidtobeanaturalmagnet.

2. Magnetsareclassifiedinto (i) Permanent magnet:Magnetsthatretaintheirmagneticpropertiesforalongerperiodoftime. (ii) Temporary magnet:Magnetsthatretaintheirmagneticpropertiesforashortperiodoftime. 3. Barmagnetsarestored inpairswiththeirunlikepolesalongsideeachotherandseparatedbya

pieceofwood.Piecesofiron,calledkeepers,shouldbekeptatthepoles. 4. AfreelysuspendedbarmagnetalwaysalignsintheNorth-Southdirection. Yes,theresultwouldbedifferentifwekeepanironneedleclosetosuchamagnetasitwillattract

theneedletowardsitselfcausingitsdirectiontochange. 5. Th emixtureofironfilingsandsandcanbeseparatedbyusingamagnetasitattractstheironfilings

fromthemixture. 6. (a) Magnet:Th esubstancethathasthepropertyofattractingobjectsmadeupofcertainsubstances

likeiron,cobaltandnickeliscalledamagnet. (b) Magnetism:Th epropertyofamagnettoattractironandnickleiscalledmagnetism. (c) Poles of a magnet:Th etwoendsofamagnetwherethemagnetismismaximumarecalledthe

polesofamagnet. (d) Self-demagnetisation:Barmagnetsarestoredinpairswiththeirunlikepolesalongsideeach

otherandseparatedbyapieceofwood.Piecesofiron,calledkeepers,arealsokeptatthepoles.Th isiscalledself-demagnetisation.

7. (a) Magnetic materials:Ironandnickle (b) Non-magnetic materials: Rubber and plastic 8. (a) Magnetic keeper are used to storemagnets as they protect themagnets from losing their

magneticproperties. (b) Two magnets should not be rubbed against each other as they can lose their magnetic

properties. 9. Propertiesofamagnet:

(i) Amagnetattractsmagneticmaterials,suchasiron,nickelandcobalt. (ii) Amagnetalwayshastwopolesandtheycannotbeseparated. (iii) Unlikepolesofamagnetattracteachotherandlikepolesofamagnetrepeleachother. (iv) AfreelysuspendedmagnetalwaysalignsintheNorth-Southdirection. (v)Th emagneticforcesaremaximumatthepolesandminimumatthecentreofthemagnet.

C. 1. Todemonstratetheattractionandrepulsionbetweenmagnets,weneedtwomagnets,threadandastand.

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Now,tieonebarmagnetwithathreadandhangitonthestand.Whenitcomestorest,taketheNorthpoleofanothermagnetneartheNorthpoleofthesuspendedmagnetandweobservethattheyrepeleachother.Now,taketheSouthpoleofanothermagnetneartheSouthpoleofsuspendedmagnetandweobservethattheyattracteachother.

Thisshowsthatlikepolesrepeleachotherandunlikepolesattracteachother. 2. ToshowthatfreelysuspendedbarmagnetalwaysalignsalongtheNorth-Southdirection,weneed

astand,barmagnetandthread. Now,hangabarmagnetonthestandwiththehelpofthreadandrotateit.Whenthemagnetcomes

torest,weobservethatitrestsintheNorth-Southdirection.Whenweagainrotatethemagnet,itwillcometorestatNorth-Southpositiononly.

ThisshowsthatfreelysuspendedbarmagnetalwaysalignsalongtheNorth-Southdirection. 3. ConstructionofMagneticcompass: Materials required: Ironneedle,cork,bowlfilledwithwaterandabarmagnet. Procedure:

(i)Magnetisetheironneedlebyusingabarmagnet. (ii) Now,insertthemagnetisedironneedleintothecorkandputthecorkinthewaterwhereit

floatsfreely. (iii)When the cork comes to rest,we observe that the needle points towards theNorth-South

direction. Working of compass: Workingof compass isbasedon theprinciple that the earth itselfbehaves like amagnet anda

magnetic object will tend to align itself with the earth’s magnetic field. In magnetic compass,magnetisedneedleatthecentrerotatesfreelyandalwaysalignsintheNorth-Southdirection.

4. Reasonsbehindthedemagnetisationofmagnet: (i) Exposuretoheat (ii) Keptinsunlight (iii) Hammered (iv) Droppedfromaheight 5. Usesofmagnets:

(i)Themagneticcompassisusedtofinddirections. (ii)Theyarewidelyusedfortreatmentinmagneticpainrelieftherapy. (iii)Theyareusedtoseparatemagneticmaterialsfromnon-magneticones. (iv)Theyarealsousedindebitcards,creditcards,etc. 6. Tomakeanironbar,amagnet,weneedanironbar,abarmagnet,ironclipsandtableandthegiven

procedure is followed: (i) Keeptheironbaronthetable. (ii) Takethemagnetandruboneofitspolesalongthelengthoftheironbar. (iii)Whenyoureachtheotherendoftheironbarliftthemagnetandbringitbacktothestarting

pointoftheironbarandagainrubitalongthelengthoftheironbar. (iv) Repeatthisprocessforabout30-40timeswiththesamepoleofthebarmagnetandtheiron

barhasnowbecomeamagnet.

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Inthisprocess,ironbarbecomesatemporarymagnet. 7. Takingcareofmagnets:

(i) Barmagnetsarestoredinpairswiththeirunlikepolesalongsideeachotherandseparatedbyapieceofwood.Piecesofiron,calledkeepers,shouldbekeptatthepoles.

(ii) Forahorseshoe-shapedmagnet,onlyonekeeperisrequired. (iii)Magnetsshouldbeheated,hammered,keptinsunordroppedfromaheight.Alltheseactivities

leadtodemagnetisationofmagnet. (iv)Magnetsshouldbekeptawayfromcellphones,televisions,radios,computersandCDs

D. ReferfiguregiveninExperiment2

E. 1. Ifweincreasethenumberofstrokes,thestrengthofthetemporarymagnetwillincrease. 2. Ifamagnetfallsdown,itwillloseitsmagneticproperties. 3. No,therewillnotbeanyeffectonthebodypartswhenamagnetisbroughtnearthebody.Th isis

becauseironispresentintheverysmallquantityandmoreoveritisnotinitsmetallicformduetowhichmagnetcannotattracttheironpresentinourbody.


1. (a),(d)and(f)

2. (b)

3. Th emagnetic compass is used to find directions andmagnets are widely used in the treatment inmagneticpainrelieftherapy.

Worksheet 2

1. (b),(c)and(e)

2. Th egivendeviceisamagneticcompasswhichisusedtofinddirections.

3. Ruboneofitspolesalongthelengthoftheneedle.

Bringitbacktothestartingpointoftheneedleandagainrubitalongthelengthoftheneedle.

Bringingsomeironclipsclosetoit.

Repeattheprocess.

98

Chapter 14Electricity and Circuits

Specific Learning Objectives Aft er the completion of the chapter, students will be able to: • Knowaboutthebasicsofelectricity. • Tellthedifferentpartsofadrycell. • Understandaboutthecharacteristicsofconductorsandinsulators. • Understandtheimportanceofconductorsandinsulators. • Commentontheconstructionandworkingofanelectricbulb. • Prepareasimpleelectriccircuitontheirown. • Identifydifferentmaterialsasconductorsandinsulators.

Materials Required

Teaching Aids: Th erearemanyteachingaidsthatcanbeusedfortheexplanationofthischapter.Wires,bulb,switch,cellsorbattery,cardboard,electricaltape,scissors,bladeandmanyotherthingsarerequiredforperformingExperiments1-4.

Warm UpTh e activitymentionedunder theWarmup sectionwill give an idea to the students about thechapter. So, the students can be asked to complete this section on page 159 on their own.Th eanswersshouldthenbediscussedintheclass.

Concept Explanation • Electric cell:Adrycellcanbeusedtoshowdifferentpartsofacelltothestudents.Th ecell

shouldbeopenedby the teacheras itscontentsmightharmthestudents.Th ecellcanbeshown to the class in3-4groups so that everyonegets a glimpseof its construction.Th edifferencebetweenaprimarycellandasecondarycellshouldbeexplainedtothestudents.

• Electric bulb:Th econstructionofanelectricbulbcanbeshowntotheclassbothwiththehelpofadiagramandbyusingasimpletorchbulb.Studentsmightbeaskedtofindouttheinertgasthatcanbeusedtofillthebulb.

• Electric circuit:Th istopichastobeexplainedwiththehelpofanelectriccircuitpreparedasmentionedinExperiment1ofthechapter.Afterexplainingthecircuittothestudentstheymightbeaskedtoprepareasimpleelectriccircuitthemselvesunderadultsupervision.Th iscanalsobetakenasaformativeassessmentactivity.Th iswillhelpdeveloppsychomotorskillsamongthestudents.Variouscomponentsofanelectriccircuitshouldbetaughtintheclass.Th estudentsshallalsobetoldaboutthedifferencebetweenanopenandaclosedelectriccircuit.

• Electric switch:Anotherinterestingactivityinthischapteristhemakingofanelectricswitch.Th umbpinsandasafetypincanbeusedveryefficientlytomakeanelectricswitchandto

99

showitsworkinginanelectricalcircuit.Again,studentsmightbeaskedtoprepareasimpleelectriccircuitwithaswitchthemselvesunderadultsupervision.Thiscanalsobetakenasaformativeassessmentactivity.

• Conductors and insulators: Experiments 3 and 4 can be used to explain this topic to thestudentswhereinthestudentscanbeshowntoidentifythegivenmaterialasaconductororasaninsulator,usingaconductiontester.Importanceofbothconductorsandinsulatorsshouldbeexplainedtothem.Theinformationmentionedas‘Teacher’stip’onpage166shouldalsobediscussedintheclass.

• Safe use of electricity:Sincethisisanexperiment-basedchapterwherestudentsworkwithelectricity, precautions related to handling the electrical appliances should be taken andinstruction to safely used the electricity should be clearly given to the students. Activitymentionedunderthesection‘Values’onpage166canbetakenasanexampleforthis.

Reinforce • A concern for the environment can be developed in the students by doing the activity

mentionedunderthe‘Lifeskills’sectiononpage167.In-textexercisesandquestionsgivenattheendshouldbediscussedintheclassastheyhelpstudentsinmemorizingthechapter.Thequestionsaskedunder ‘HOTS’and‘Picturebasedquestion’willdevelopthinkingandreasoningabilitiesinthestudents.

Explore • Studentscanbeaskedtodothe‘Project’and‘Let’sspeak’activityontheirowntogetabetter

knowledgeofthechapter.

100

1. Identify the various parts of a bulb.

(a)___________(b)___________

(c)___________

(d)___________

(e)___________

2. Give two examples for each of the following. (a) Conductors (b) Insulators

____________________ ____________________

____________________ ____________________

(c) Secondarycells (d) Devicesthatusessolarcells

____________________ ____________________

____________________ ____________________

3. List the diff erent components of an electric circuit.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

Worksheet-1

101

1. Th e fi gures given below show a cell connected to a bulb in diff erent ways. Identify in which of the arrangements the bulb will not glow and mention the reason.

______________________________________________________________

2. Mention two points on the safe use of electricity.

______________________________________________________________

______________________________________________________________

______________________________________________________________

3. Identify the components of electric circuit being mentioned in the following statements.

(a)Itcontrolstheflowofcurrentinthecircuit.______________________

(b)Itisthesourceofelectriccurrent.__________________________

(c)Ituseselectricalenergy._________________________

(d)Ittransferstheelectricalenergyfromonecomponenttotheother.__________

Worksheet-2

(a) (b)

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A. 1. (a) AlessandroVolta(b)poor(c)electriccell(d)closed(e)switch 2. Column A Column B

Filament of a bulb TungstenConductor Iron,copper,silverInsulator Plastics,glass,woodCombinationofcells BatteryPathofcurrentflow ElectriccircuitRechargeablecells SecondarycellsNon-rechargeablecells Primarycells

3. (a) Plastics (b) Wood (c) Switch (d) TungstenB. 1. Inanelectriccell,themetalcapononesideofthecellisthepositiveterminal,whilethemetaldisc

attheothersideisthenegativeterminalofthecell.Th eyaremarkedas‘+’and‘–’,respectively. 2. Twotypesofcells:

(i) Primary cells:Th eycannotbeusedagain,thatis,theycannotberecharged.Th esearesingleusecell.Forexample:Drycell

(ii) Secondary cells: Th ey can be recharged and can be used again. Th ese are also known asrechargeablebatteries.Forexample:Lead-acidbatteriesusedincars.

3. Conductors help in the conduction of electricity andheatwhile insulators protect us from theelectricshockastheydonotallowtheflowofcurrentfromelectriccircuittoourbody.

4. Componentsofelectriccircuit: (i) Sourceofelectriccurrentsuchaselectriccellorbattery (ii)Wiresmadeofmetalslikecopper,aluminium,etc. (iii) Electricalappliancesuchasbulb (iv) Anunbroken loopofwire running fromone terminalof the source, through theelectrical

appliance,backtotheotherterminalofthesource. (v) Aswitchorakeytocontroltheappliance. 5. Conductors:Copper,silver,aluminium Insulators:Wood,plastic,glass 6. Th edifferencebetweencellandbatteryisthatbatteryisthecombinationoftwoormorecells. 7. (a) Electriccell (b)Switch (c)Wiresmadeupofcopper 8. No,wecannotcover thebarepartof theelectricwirewithaluminiumfoilbecause it isagood

conductorofelectricity.Tocoverthebarepartofelectricwireweneedaninsulator. 9. Whentheelectriccircuitallowscurrenttoflowthroughitsothattheelectricalapplianceconnected

toitworks,thenitissaidtobeclosed. 10. (a)Electric cell: It is thesourceofelectriccurrent thatconvertschemicalenergystored in it to

electricalenergy. (b) Electric circuit:Th ecompletepaththatallowscurrenttoflowthroughitiscalledanelectric

circuitoranelectricpath. (c) Battery: Th ecombinationoftwoormoreelectriccellsiscalledbattery. (d) Switch or key:Adeviceinanelectriccircuitthatcontrolstheflowofelectriccurrentthrough

electriccircuitiscalledswitch.

103

11. (a)Closed circuit Open circuit

When the electric circuit allows current toflowthroughitsothattheelectricalapplianceconnected to it works, then it is said to beclosed.

When the electric circuit allows currentto flow through it so that the electricalapplianceconnectedtoitworks,thenitissaidtobeclosed.

(b)

Conductors InsulatorsThesubstancesthatallowtheflowofcurrenttopassthroughthem.Forexample:Copper,silver,aluminium,etc.

Thesubstancesthatdonotallowtheflowofcurrenttopassthroughthem.Forexample:Plastics,glass,wood,etc.

12. (a) Toavoidtheelectricalshock,thehandlesofthescrewdriversusedbyelectriciansareusuallymadeofplastic.

(b)When the switch is inONposition, itmeanscircuit is closedandcurrentflows through itwithoutanyobstructionduetowhichelectricbulbconnectedtoitglows.

(c) Rubberslippersandglovesareinsulators,i.e.,theydonotallowtheflowofcurrentthroughthem.Sotheyarewornwhilecarryingoutelectricalrepairtoavoidelectricshock.

(d) Anelectricbulbdoesnotglowevenifitisconnectedtothecell.Thisisbecause,switchisinOFFpositionwhichmeansnocurrentflowsthroughtheelectriccircuit.

(e)Metalwirescarryingelectricityarecoveredwithplasticbecauseplasticisaninsulatorwhichdoesnotallowtheflowofcurrentthroughit.

C. 1. Componentsofelectricbulb (i) Filamentofbulbismadeofmetalcalledtungsten. (ii)ThefilamentissupportedbytwothickwiresformingaV-shapedstructurewhichareconnected

tothetwoterminalofthebulb. (iii) Oneterminalispresentonthemetalcaseofthebulbandtheotherterminalisthemetaltipat

thebaseofthebulb. (iv)Thereisaninertgasinsidethebulbwhichpreventstheburningoffilamentwhenitheatsup. Referfigure14.4onpage161 2. Todesignanelectriccircuit: Materials required:Electricwires,electriccell,smalltorchbulb,insulationorelectrictape,apair

ofscissors,thumbpin,safetypin Procedure:

(i) Cutthewireintotwopiecesandexposetheendsoftwowiresusingscissors. (ii) Takeonewireandattachthistothepositiveterminalofcell. (iii) Attachtheotherendofthewiretooneoftheterminalsofthebulb. (iv) Takeanotherwire andattach this to the second terminalof thebulb and turn its free end

aroundathumbpin. (v) Nowinsertthepinintheringofthesafetypininsuchawaythatasafetypincanmovefreely. (vi) Nowtakeanotherwireandconnectitsfirstendtothenegativeterminalofthecellandturnits

freeendtowardsthesecondthumbpin. Inthiscase,thesafetypinactsasaswitchaswhenittouchesthesecondthumbpin,electriccircuit

willgetcompletedandthebulbwillglow.

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3. Precautionstobetakenwhileworkingwithelectricity: (i) Nevertouchtheelectricalappliancewithwethands. (ii) Neverconnecttoomanydeviceswithasinglesocketormultiplug. (iii) Alwayswearrubbergloveswhileworkingwithelectriccircuits. 4. Totestwhetherthegivenmaterialisaconductororaninsulator Forthis,werequire3piecesofelectricalwires,pencilcell,smalltorchbulb,electricaltape,apairof

scissors,bladeandtestingmaterialsuchaswoodpiece. Procedure: Connectthetwoterminalsofthebulbwithtwoseparatewiresusinganelectricaltape.Connectthe

freeendofoneofthesewirestothepositiveterminalofthepencilcell.Nowconnectthenegativeterminalofthecellwithoneofthetwoendsofthethirdwire,leavingtheotherendofthewirefree.

Nowyouhavetwowireseachwithoneendfree.Connecttheseendstocheckwhetherthecircuitisworkingornot.Nowtakethematerialtobetestedandtouchthefreeendsoftwowireswithit.

Ifthebulbglows,thenthematerialisaconductorandifitdoesnotglow,itmeansthematerialisaninsulator.

5. Workingofanelectricaltorch: Inanelectrical torchwhentheelectriccurrentflows throughthebulb, thefilamentof thebulb

glowsandproduceslight.Ifthereisanykindofbreakageinthefilament,thenthebulbwillnotglow.Suchabulbissaidtobefusedandneedstobereplaced.

D. Whenacopperwireandanaluminiumfoilareusedthenthebulbwillglow.E. 1. Humanbodyconsistsof70-75%waterwhichisagoodconductorofelectricity. 2. Waterisagoodconductorofelectricitysoitshouldnotbeusedtoextinguishthefirescauseddue

toelectricity. 3. Electricwiresatourhomearewithinourreach.Sotoavoidelectricalshocktheyarecoveredwith

insulators.Butthewiresconnectedtotheelectricpolesareveryfarfromanyhumancontact,sotheyarebare.

4. (a) Intensityofaglowingofbulbwilldecreaseifonemorebulbisadded. (b)Th erewillbeanincreaseintheintensityofglowingofbulbifonemorecellisaddedinthe

circuit.


1. (a)Glassbulb(b)Tungstenfilament(c)Inertgas(d)Cap(e)Terminals

2. (a)Copper,Silver (b)Air,Wood (c)Leadacidbattery,Lithiumbattery

(d)Calculatorsandsatellites

3. Electriccellorbattery,bulb,wiresandaswitchorakeyWorksheet 2

1. In(b),thebulbwillnotglowbecausetheelectriccircuitisincomplete.

2. Neverplaywithelectricalwiresandswitches.

Neverconnecttoomanydeviceswithasinglesocket.

3. (a)Switchorkey (b) Battery (c) Bulb (d) Wire

105

Chapter-15Water

Specific Learning Objectives Aft er the completion of the chapter, students will be able to: • Learnaboutdifferentsourcesofwater. • Knowabouttheimportanceofwaterforlivingorganisms. • Understandthewatercycleinnature. • Understandthecausesandeffectsofdroughtandflood. • Appreciatetheimportanceandmethodsofwaterconservation.

Warm UpTh echaptershouldleaveanimpactonthestudentsonthetoimportanceofconservationofwater.ToinculcatethisfromtheverybeginningofthechapteritisimportanttodiscusstheactivitygivenundertheWarmsectionwiththestudents.

Concept Explanation • Sources of water: Different sources of water should be discussed with the students.Th e

percentagedistributionofthesesourcespresentontheearth’ssurfaceshouldalsobetoldtothem.

• Uses of water:Water is very important for thehumanbody. Students are already familiarwiththeimportanceofwatertohumanbodyastheyhavealreadydonethisintheirpreviouschapters.Th eyarealsoacquaintedwiththeimportanceofwatertoplants,sothesetopicscanbetaughtasaclassdiscussionwherestudentsshallgiveanswersonthistopic.

• Diff erent forms of water:Studentshavepreviousknowledgeofthistopicfromchaptersalreadydone.Th eycananswerthequestionslike:Howicecanbeconvertedtowater,watertosteam,steambacktowaterandwatertoice.Th eycanevendefinetheprocesseslikeevaporationandcondensation.Th istopiccanagainbegivenastudent-centeredapproach.

• Water cycle:Th isisaveryimportanttopicandshouldbeexplainedtothestudentsintheformofdifferentsteps.Th ediagramshouldalsobecoveredintheclass.Studentsarefamiliarwiththedifferentstepsbutmaynotabletolinktheminacyclicformtoshowwatercycle,heretheteachershouldexplainthislinktothestudents.

• Natural disasters:Floodsanddroughtsshouldbeexplainedtothestudentsalongwiththeircauses and impacts. Students should be able to answer questions the effects of these twonaturaldisasters.Termslikefamineandepidemicshouldalsobetaught.

• Water conservation: Itisimportantforthestudentstounderstandtheconservationofwater.Th eyshouldappreciatetheimportanceofwaterandthemeanstoconservewater.Methodslikerainwaterharvestingshouldbeexplainedtothestudents.Studentscanalsolistthepointsofwaterconservationfromtheirside,apartfromtheonesmentionedinthechapter.

106

Reinforce • Students should understand the importance of saving water. Activitiesmentioned under

‘Teacher’s tip’, ‘Values’ and ‘Life skills’ will help in inculcating a sense of responsibility towards the environment in the students.Picture-basedquestiononpage180willhelp inrecapitulatingthestepsofwatercycle.Thein-textandtheexercisequestionsgivenintheendshouldbediscussedintheclass.TheHOTSquestionswillhelpindevelopingThinking skills amongthestudents.

Explore • StudentsshouldbeaskedtoperformActivity1onpage173ontheirowntounderstandthe

wastageofwaterdoneatlevel.Thiswillhelpindevelopingempathytowardstheenvironment.Theactivitiescoveredinthe‘Innovator’scorner’,‘Project’and‘Let’sspeak’willhelpstudentstofurtherexploreregardingimportanceofwater.

107

1. Look at the given picture of water cycle and fi ll in the spaces with the appropriate process.

a._________________

b._________________

c._________________

d._________________

e._________________

f._________________b.

a.

c.

d.

e.

f.

2. Write two methods of water conservation.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

3. Fill in the blanks so as to complete following sequence.

Ice Water Steam

Worksheet-1

108

1. Write the diff erent steps of water cycle.

______________________________________________________________

______________________________________________________________

______________________________________________________________

2. What is drought and fl ood?

______________________________________________________________

______________________________________________________________

______________________________________________________________

3. Write two uses of constructing dams.

______________________________________________________________

______________________________________________________________

______________________________________________________________

4. List diff erent sources of water.

______________________________________________________________

______________________________________________________________

______________________________________________________________

5. Defi ne the following.

(a) Famine __________________________________________

(b) Epidemic __________________________________________

Worksheet-2

109


A. 1. (a) False (b) False (c) True (d) True (e) True 2. (a) Lakesandponds

(b) Rooftoprainwaterharvestingandsurfacerainwaterharvesting (c) Rainandsnow (d) Ice(solid)andsteam(gaseous) (e) Typhoidandcholera (f) Floodanddraught

B. 1.

Evaporation CondensationTh e process of conversion of water into itsvapourformiscalledevaporation.

Th e process of conversion of water vapourintoitsliquidformiscalledcondensation.

2. Iftwometalcontainersarefilledwithwaterandoneiskeptinsunlightandtheotherintheshade,thenaftersometime,waterlevelinthemetalcontainerkeptinsunlight,willdecrease.Th isisduetotheprocessofevaporation.

3. Damsarethehugewallsbuiltonacourseofrivertostorerainwatertobeusedatthetimeofneed.Th ereservoirinadamcollectswaterwhichisusedduringdroughts.

4. Th ewarmthofthesunquickenstheprocessofevaporationandtranspirationofwatertoformwatervapourswhichformcloudsoncondensationandfinallyonprecipitation,cloudsformrain.Th israinwatergetscollectedintheriversandoceansandagainevaporatestoformvapour.Inthiswaywatercyclecontinueswiththehelpofsun.

5. Sea water contains high amount of salts andminerals dissolved in it whichmakes it unfit fordrinkingandotherpurposes.

6. Advantagesofrainwaterharvesting: (i) Itrestoresthesurfacewaterbacktonormallevels. (ii) Itrechargesgroundwater. (iii) Itmaintainsthelevelofwatertable. (iv)Th e collected rainwater can be used formany purposes such as washing clothes, cleaning

dishes,etc. 7. Water pollution:Th e contamination of thewaterwith the harmful substances such as sewage

andwastethatbringthechangesinthephysicalandchemicalpropertiesofwateriscalledwaterpollution.

8. Whenwaterevaporates,itformsvapourswhichriseupandformtinydropletsofwater.Th esetinydropletscollecttoformclouds.

C. 1. Th erearetwotypesofrainwaterharvesting: (i) Rooft op rainwater harvesting: It is a systemof collecting rainwater from roofsof thehouse

or building. It is either stored in a tank or is allowed to seep into the soil to recharge thegroundwater.Th ewatermaycontainssomeimpurities.Th isisaneffectiveandlowcostmethod.

(ii) Surface rainwater harvesting: Th e rainwater which is flowing on the roads and drains iscollectedandisusedtorechargeandrefilldeeppits.Th iswaterseepsinsidethegroundslowlyandreplenishesthewatertable.

110

2. Stepsinwatercycle: (i) Evaporation and transpiration:Water present in the oceans, rivers, lakes, etc. is converted

intovapourformduetotheheatfromsunlight.Alsoplantslosewaterthroughtheprocessoftranspiration.

(ii) Condensation: The water vapours rise up and condense to form tiny droplets which oncollectionformacloud.

(iii) Precipitation:Whencloudscannotholdanymorewaterdroplets,theyburstandthedropletscomedownontheearth’ssurfaceintheformofrain,snow,etc.

(iv) Percolation:Water comes back to the earth’s surface, thus completing thewater cycle.Theseepingofwaterintothegroundiscalledpercolation.

3. Yes,thethreestatesofwaterareinterconvertibleandthiscanbeexplainedas:

4. Differentwaysofconservingwater: (i) Uselesswaterfordailyactivitieslikecleaning,washing,bathing,etc. (ii) Checkleakingpipesortapsatthehomes. (iii) Recyclewaterforotherpurposebeforethrowingit. (iv) Encouragewaterharvestingpractices. (v) Checkwaterpollutionbytreatingsewageandwastebeforethrowingtheminrivers. 5. Harmfuleffectsofflood:

(i) Itcausesthelossoflifeandproperty. (ii)Watercontaminationoccursduetodamageofsewagedisposalfacilitiesanddeathofhumans

andanimals. (iii) Itcauseswaterloggingwhichresultsinthespreadofdiseasessuchascholera,yellowfever,etc. (iv) Italsoleadstosoilerosion. (v) Itdamagestheagriculturalfields,leadingtoreducedcropyield. Harmfuleffectsofdrought:

(i) Bothsurfacewaterandgroundwaterbecomescarce. (ii) Soildriesupandplantsandcropscannotgrow,resultingintheshortageoffoodintheregion. (iii) Livestockandotheranimalsdieintheabsenceoffoodandwater. (iv)Watersourcesoftheregiontendtodryup. (v) Forestfiresareanotherconsequenceofdrought. 6. Usesofwater:

(i)Waterisusedbyhumansandanimalsforcarryingoutvariousbodyprocessessuchasbloodandnutrientcirculation,removalofwaste,etc.

(ii)Waterisneededfordailyactivitiessuchascooking,washing,etc. (iii) Itservesasthehabitatformanyanimalsandamediumoftransportation. (iv) Itisrequiredbyplantsfortheprocessofphotosynthesis. (v) Itisalsousedforindustrialandagriculturalpurposes.

D. (a) Sun (b) Evaporation (c) Condensation (d) Precipitation (e) Runoff (f) Percolation

111

E. 1. Tinywaterdropletsarecollectedontheundersideoftheplate.Th ishappensduetocondensationofsteamthatrisesfromthehotmilkwhichontouchingthecoolplate,condensesandformstinywaterdroplets.

2. Oceansarebiggestsourceofwateronearthbutthiswaterisunfitforuse.Watercyclehelpsinusingthiswaterpresentinoceansbythecausingrainswhichreplenishthelakes,river,ponds,etc.Ifwatercycledidnotoperate, thendue to lackof rainfalls, drought-like conditionswouldoccurwhichwoulddisruptlifeonearth.

3. Pricesofthingsriseupwhenthereismoredemandthansupply.Duringthefloodanddraught,thecropfieldsaredestroyedduetowhichthereisadecreaseinthesupplyoffooditemsintothemarketandtheirpricesriseup.

4. Treesandvegetationpreventthelossofwaterfromwatertablebyevaporation.Vegetationmakesthesoilporouswhichincreasestherateofpercolationandenricheswatertable.


1. (a)Sunlight (b) Evaporation (c) Condensation (d) Precipitation

(e)Evaporation (f) Groundwater

2. Uselesswaterfordailyactivitiessuchascleaningandwashing.Checkleakingpipesandtapsatyourhomes.

3. (a)Heating (b) Evaporation (c) Freezing (d) CondensationWorksheet 2

1. Evaporation,condensation,cloudformation,precipitationandpercolation

2. Drought:Itisaconditionthatoccurswhenanareareceiveslessornorainfallforalongperiod.

Flood:Prolongedperiodsofheavyrainsinanareacanresultinaconditioncalledflood.

3. Damspreventfloodsandalsoconservewaterforirrigation.

4. Rainwater,groundwater,surfacewaterandseawater.

5. (a)Th eprolongedlackoffoodinaregion.

(b)Adiseaseaffectingnumberofpeopleatthesametime.

112

Chapter 16Air

Specific Learning Objectives Aft er the completion of the chapter, students will be able to: • Understandthecompositionofair. • Explainthetermslikeatmosphere,humidity,spiracles,stomata,pollution. • Understandtheimportanceofdifferentcomponentsofairforlivingbeings. • Appreciatehowanimalsandplantsmaintainabalanceinnature. • Commentondifferentrespiratorysystemspresentinlivingbeings. • Knowaboutsomeofthefactorsthatcausesairpollution.

Materials Required

Th e teaching aids that can be used to explain the chapter are the ones required to performExperiments1and2.

Warm UpStudentsarealreadyfamiliarwiththetermatmosphere.Th eyalsoknowaboutdifferentlayersoftheatmosphere.Th ereforeintroductoryquestionsbasedonthiscanbeaskedtobeginthechapter.Th eWarmupsection’sactivitywillfurtherhelpthemtobecomefamiliarwiththechapter.

Concept Explanation • Components of air:Th estudentsshouldbeexplainedaboutvariousmajorgasespresentin

theair.Th eimportanceoftheseforlivingorganismsshouldalsobetaughtintheclass.Th estudentswillbeabletocommentonsomeoftheusesofgaseslikeoxygenandcarbondioxideas theyhave learntabout this in theirpreviouschapters.Experiment2canbeperformedinclasstoshowtheimportanceofoxygen.Th iswillalsohelpindevelopinginterestofthestudentsintheclass.

• Air supports life: Th erespiratoryorgans indifferentorganismsshouldbeexplainedtotheclass.Th eyshouldbetoldthatthetypeofrespiratoryorganvariesaccordingtothehabitatofthelivingorganism.Atemporarymountofstomatacanbepreparedandcanbeshowntothestudentsinsciencelab.Th iswillmakethechapterinterestingtothem.

• Balance of oxygen and carbon dioxide:Th is canbe shown to the students inacyclic formthatcoversthedifferentprocessesinvolved.Studentscanbeaskedtodefinerespirationandphotosynthesistofacilitateatwowayinteraction.

• Air pollution:Itisimportantforthestudentstoknowthecausesandeffectsofairpollution.Studentsmightbeaskedto list thevariouscausesofairpollutionfromtheirsideandnotnecessarilyfromthebook.Th iswillhelpindevelopingthinkingabilitiesamongthem.

113

Reinforce • Studentsshouldbeaskedtocompletetheexercisesgiveninthechapter.Thisshouldbelater

discussedintheclass.Theilleffectsoftheairpollutionshouldbediscussedintheclass.Thiswilldevelopaconcernfornatureamongthem.The‘Picturebased’andthe‘HOTS’questionswilldevelopthinkingskillsamongthem.

Explore • TheActivitymentionedunderthe‘Innovator’scorner’sectiongivenonpage190,willprove

tobeinterestingtothestudents,whereintheywillexplorethemethodtoperformthisactivityontheirown.Thiscanbeusedasaproject-basedformativeassessmentactivity.

114

1. In the given pie chart, fi ll in the blanks with suitable components of air.

(c)

(b)(a)

2. Match the organisms with their respiratory organs.

COLUMN A COLUMN B

Earthworms Stomata

Cockroaches Lungs

Fishes Moistskin

Plants Gills

Mammals Spiracles

3. Mention any two respiratory diseases that can occur due to air pollution.

______________________________________________________________

______________________________________________________________

______________________________________________________________

4. Defi ne humidity.

______________________________________________________________

______________________________________________________________

Worksheet-1

115

1. Two boys Ram and Sonu caught butterfl ies and captured them in two separate bottles as shown below. Next day Sonu found his butterfl y to be dead but Ram’s butterfl y was alive. Can you tell the reason behind this?

______________________________________________________________

______________________________________________________________

______________________________________________________________

2. Identifythecomponentsofairinthefollowingstatements. (a) Neededforthesynthesisofproteins.__________________ (b) Requiredfortheprocessofphotosynthesisbytheplants._______________ (c) Requiredforrespirationandburning.__________________

3. Write two practices that can be followed to control air pollution.

______________________________________________________________

______________________________________________________________

______________________________________________________________

4. Defi ne air pollution.

______________________________________________________________

______________________________________________________________

Worksheet-2

116


A. 1. (a) Aircontainsdifferentamountofwatervapour. (b) Oxygengassupportsburning. (c) Airisamixtureofgaseslikenitrogen,oxygen,carbondioxide,etc. (d) Airhasmassandoccupiesspace. (e)Whenweheatwater,itexpelsthedissolvedair. 2. Column A Column B

Lungs HumansStomata PlantsGills FishSkin Earthworm

B. 1. Atmospherecontainsairwhich isamixtureofgases likenitrogen,oxygen, carbondioxide, etc.Oxygenisusedforrespirationinplantsandanimalswhilecarbondioxideisusedbyplantstomaketheirfoodbytheprocessofphotosynthesis.

2. Fishbreathewiththehelpofgillswhicharecapableoftakingdissolvedoxygenfromwater. 3. Whalesanddolphinsdonothavegillsforbreathing,insteadtheyhavelungs.Sotheycometothe

surfaceofwaterregularlytofilltheirlungswithair. 4. Polluted air containsmany toxic gases which on inhalation cause respiratory diseases such as

asthma,lungcancer,bronchitisandeyediseases. 5. Nitrogendoes not play any role in the process of respiration in living beings.Also it does not

supportburning. 6. Compositionofair: Nitrogen-78% Oxygen-21%Othergases-1%C. 1. Uses of air:

(i) Aircontainsoxygenwhichisneededbyhumansandanimalsforbreathingandrespiration. (ii) Aircontainscarbondioxiderequiredbyplantsforphotosynthesis. (iii) Airhelpsinseeddispersal. (iv) Ithelpsinburningasoxygensupportsburning. (v) Ithelpsingeneratingelectricitythroughwindmills. 2. Air occupies space: Toprovethis,takeabucketfullofwater.Nowdiptheemptyplasticbottleverticallyinthebucket.

Wewillobservethatwaterdoesnotenterthebottle.Nowtiltthebottlealittleandweobservethatairbubblesstartcomingoutofitandwaterentersthebottle.Th isindicatesthatairispresentinemptywaterbottle

Air contains water vapour: Totest this,fillaglasstumblerwithiceandkeepitatroomtemperatureforfewminutes.After

sometimeweobservethattherearetinywaterdropletsonthesurfaceofthetumbler.Th isisduetothepresenceofwatervapourwhichcondensesontouchingthecoolsurfaceoftumblerandformsdropletsofwater.Th isshowsthatairhaswatervapour.

3. Plantstakecarbondioxidetoproducefoodandtheygiveoutoxygenasaby-product,whichisusedbyanimalsforbreathingandrespiration.Also,animalsexhalecarbondioxideduringbreathing,whichistakenupbytheplantsforphotosynthesis.Inthisway,plantsandanimalsmaintainthebalanceofgases.

117

4. (a) Aswemoveup,theairgetsthinneranditbecomesdifficulttobreathe.Becauseofthisreason,mountaineerscarryoxygencylinderswiththemwhileclimbingthemountains.

(b) Earthwormscomeoutofsoilinrainyseasontobreatheairasthesoilpocketsbecomefilledwithwaterthatunablethemtobreathe.

(c) Plants die inwaterlogged conditions as excesswaterlogging causes decrease in the oxygensupplywhich leads to thedecreased respiration, causingplants todie.Excessofwater alsopromotesthegrowthofharmfulmicroorganisms.

(d) Stomatapresenton leaf surfacehelp theplants in the exchangeof gases and transpiration.Since,aquaticplantsdonothavetheneedtoexchangegases,theydonothavestomata.

(e) Carbondioxideisusedbyplantstopreparetheirfoodbytheprocessofphotosynthesis.Duringthisprocess,plantsgiveoutoxygenastheby-productwhichisusedbyanimalsandhumansforrespiration.So,thepresenceofcarbondioxideisbeneficialforlivingbeings.

5. Role of atmosphere: (i) Itactsasaprotectiveshieldforthelivingorganisms. (ii) Itmaintainsthetemperatureoftheearthbetweendayandnight (iii) IthastheozonelayerthatprotectsusfromtheharmfulUVradiationscomingfromsun. (iv) Italsohelpsinmaintainingthewatercycle.

D. A. Sunrays B. Oxygen C. Respiration D. Carbondioxide E. Photosynthesis F. Waterandminerals

E. 1. Atnight,treesrespire,i.e.theybreatheinoxygenandgiveoutcarbondioxide.Inhalationofcarbondioxideisharmfulforlivingbeings,soitisnotadvisabletosleepunderatreeatnight.

2. Busyroadhasheavytrafficwhichmeansthatamountoftoxicgasesproducedbytheexhaustofvehiclesishighintheair.Asinhalationofthesegasescreatesrespiratorydiseasessuchasasthmaorlungcancer,soatrafficpolicemanwearsamaskonhisnose.

3. Hotairislightinweight,soitrisesup.Toexpelhotgasesfromtheroom,ventilatorsaremadeclosetotheceilingtomaintainthetemperatureoftheroom.

4. On the night of Diwali, people celebrate the festival by bursting crackers which produce veryharmfulgasesintheatmosphere.Duetotheseharmfulgases,itisdifficulttobreatheonthenightofDiwali.

Answers to WorksheetsWorksheet 1 1. (a)-Nitrogen71%,(b)-Oxygen21%and(c)-Othergases1% 2. Earthworms–Moistskin,Cockroaches–Spiracles,Fishes–Gills,Plants–Stomata,Mammals–Lungs 3. Asthamaandlungcancer 4. Th eamountofwatervapourpresentintheairataparticulartime.Worksheet 2 1. Ram’sjarhadholesinitthroughwhichaircouldpass.Th erefore,butterflyinRam’sjarwasaliveasitgot

oxygentobreathe. 2. (a)Nitrogen (b) Carbondioxide (c) Oxygen 3. Byplantingmoretreesandrecyclingplasticinsteadofburningthem. 4. Th emixingofundesirablesubstancesinquantitiesthatareharmfultolivingbeingsinair.

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Chapter 17Garbage in Garbage out

Specific Learning Objectives Aft er the completion of the chapter, students will be able to: • Learnaboutdifferenttypesofwasteandthesourceoftheirgeneration. • Enumeratedifferencebetweenbiodegradableandnon-biodegradablewaste. • Learnaboutsomesimpletechniquesofwastemanagement. • Analysethehazardsbehindthecollectionofwasteintheenvironment. • Evaluatetheimportanceof3R’sinwastemanagement. • Citedifferentmethodsofwastedisposal.

Materials Required

Teaching Aids: Th eteachingaidsthatcanbeusedtosupportthischapteraretheonesrequiredtoperformvariousactivitiesandexperimentsmentionedinthechapter.

Warm UpTh emainobjectiveof this chapter is tomake the studentsunderstand the importanceofwastemanagement.Th ey should know that waste has to be reduced at various levels and should beproperlydisposedof.So,tobeginthechapterthestudentsshouldbeaskedtofirstcompletethetaskgivenintheWarmupsection.

Concept Explanation • Types of waste: Th e difference between the two types of waste should be made clear to

thestudents.StudentsmightbeaskedtoperformExperiment1athomeor thismightbeperformedmuchearlierbeforestartingthechapterandtheresultcanbeshowntothemlater.

• Waste management: Different steps in thewastemanagement should be discussed in theclass.Managementofbothbiodegradableandnon-biodegradablewasteshouldbetaughttotheclass.Variousmethodslikelandfillsandcompostingshouldbeexplainedtotheclass.Avermicompostpitcanbepreparedintheschoolwiththehelpofthestudentsandthiscanalsobetakenupasaschoolactivity.Th iswilldevelopinterestinthesubjectandalsoinculcatesocialvaluesandlovefornatureamongthestudents.

• 3R’s: Th ethreeR’sshouldbediscussedintheclass.Th epointsincludedunderreduce,reuseandrecycleshouldbeexplainedtotheclass.Studentsshouldbetoldthatplasticsareharmfulfor theenvironmentand theirdisposal is aproblem, so they shouldbe recycledas far aspossible.Th eactivityconcernedwiththerecyclingofpaper(givenonpage197)shouldbeshowntothestudents.

• Methods to reduce waste:Pointsconcernedwiththereductionofwasteshouldbeexplainedtothestudents.Th eymightbeaskedtolistsomepointsfromtheirsidealso.Th iswillmaketheclassinteractive.

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Reinforce • Thenewwordsgivenunder‘WordDrop’shouldbereadintheclassforaquickrecapitulation

ofthechapter.Thestudentsshallcompletetheexercisesgiveninthechapterandthesameshall also be discussed with them.The activities and the experiments mentioned in thechaptercanbetakenasagroupactivityforthestudents.Thiswilldevelopteamworkskill,empathytowardsenvironmentandsocialskillamongthestudents.

Explore • Studentscanfindoutmoreabouttheharmscausedbytheplasticstotheenvironmentapart

fromtheonesmentionedinthechapter.Theactivitygivenunderthe‘Innovator’scorner’willbehelpfulbothforthestudentsandtheschool.

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(a) Biodegradablewaste (b) Materialsthatcanberecycled

___________________ ___________________

___________________ ___________________

(c) Non-biodegradablewaste (d) Nutrientspresentinwormcastings

___________________ ___________________

___________________ ___________________

2. Write two practices that can be followed to reduce waste.

______________________________________________________________

______________________________________________________________

______________________________________________________________

3. How one can manage non-biodegradable waste?

______________________________________________________________

______________________________________________________________

______________________________________________________________

4. Defi ne segregation of waste.

______________________________________________________________

______________________________________________________________

______________________________________________________________

Worksheet-1

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1. Arrange the following statements in proper sequence to obtain recycled paper.

(a) Spreadthepaperonawiremeshasshownandpressittosqueezeouttheexcesswater.

(b) Take the paper out and crush it with the help of amortar and pestle till itbecomessoft.Th isiscalledthepaperpulp.Youcanalsogrinditinamixer.

(c) Collect some amount of waste paper like old newspapers, magazines, usednotebooks,etc.

(d) Yourhandmaderecycledpaperisready. (e) Tearthemintosmallpiecesandsoaktheminwarmwaterfor6-7hours. (f) Turnthemeshupsidedownonasmoothsurfacesothatthepaperpulpspreads

evenly.Now,putsomeweighttoitonletitdrycompletely. Correctsequenceis___________________________________.

2. Whyisburningofpaperandleavesnotgoodforenvironment?

______________________________________________________________

______________________________________________________________

______________________________________________________________

3. Writethestepstomakeavermicompostpit.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

4. Definewormcasting.

______________________________________________________________

______________________________________________________________

Worksheet-2

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A. 1. Arrangementofstepsinthecorrectsequence (d) Digapit (c) Addkitchenwaste (f) Putredwormsinthepit (g) Addathicklayerofsoil (e) Coveritwithalayerofgrass (a) Sprinklesomewatertokeepitmoist (b) Obtainmanureafterabout45days 2. (a) Leftoverfoodandvegetablepeels

(b)Metalandbatteries (c) Kitchenwasteandplantparts (d) Paperandplastic (e)Wastewaterandusedoil (f) Plantpartsandeggshells

B. 1. Onthebasisofdegradability,wastecanbeclassifiedintotwotypes: (i) Biodegradable waste: Vegetablepeels (ii) Non-biodegradable waste: Metalparts 2. Th epractiseofseparatingbiodegradablewastefromnon-biodegradableiscalledthesegregationof

waste. Itisimportanttosegregatewastesothatbiodegradablewastecanbeusedformakingmanurewhile

non-biodegradablewastecanberecycledandusedagain. 3. Largerareasusedforwastedisposalarecalledlandfills.Th eyarealsoknownasdumpinggrounds.

Solidwastelikegarbageisdumpedorburiedinthegroundinsuchawaythatitdoesnotharmtheenvironment.Itisoneoftheefficientwaysofdisposingofwaste.

4. Compostinginwhichredwormsactonwastesanddegradethemiscalledvermicomposting.Th eendproductiscalledvermicompostwhichisagoodmanureasitcontainsnitrogen,phosphorusandpotassiumwhichareimportantforthegrowthofplants.

5. Plasticposesaseriousthreattotheenvironmentasitisanon-biodegradablewasteandcannotbedegradedbymicroorganisms.Hence,itkeepsonaccumulatingandcausepollutioninenvironment.

So,itshouldberecycledandusedagain. 6. Paperisrecycledintherecyclingfactoriestomakenewitemslikepackagingmaterialsorrecycled

paperwhichcanbeusedagain. 7. Weshouldusebothsidesofpaperbeforethrowingitinthedustbin. 8. (a) Paperismadefromtrees,sorecyclingofpaperhelpsinpreventingthecuttingoftreeswhich

savestheenvironment. (b) Plastic bag is non-biodegradablewhich cannot bedecomposedbymicroorganisms, thus it

shouldnotbedumpedintocompostpit. (c) Invermicompostpit,redwormsactonorganicwaste.Sinceredwormsneedmoistureandair

tosurvive,thevermicompostingpitshouldbekeptmoistandaerated. (d) Biodegradablewastecanbedecomposedbythemicroorganisms,thusitdoesnotpollutethe

environmentandiscalledgreenwaste.

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(e)Theendproductofvermicomposting iscalledvermicompostwhich isagoodmanureas itcontainsnitrogen,phosphorusandpotassiumwhichareimportantforthegrowthofplants.

(f) Recyclinghelpsinreusingofnon-biodegradablesubstanceslikeplasticwhichotherwisewouldkeeponaccumulatingandpollutetheenvironment.

C. 1. Digapitinthegroundandputsomeplasticbagsinit.Nowcoverthiswithalayerofsoil.Sprinklesomewateronit tokeepthesoilmoist.Nowdigthepitafter35-40daysandyouwillfindthatplasticbagshavenotbeendegradedbymicroorganism.Thisactivityshowsthatplasticsarenon-biodegradable.

2. (i) Humanandanimalwasteshouldnotbedumpedintolandfills. (ii) Hazardousmaterialshouldnotbedumpedintolandfills. (iii)Wasteshouldbedumpedinsuchawaythatitdoesnotharmtheenvironment. (iv)Thewasteshouldbecoveredwithalayerofsoiltoallowdecomposition. 3. Makingavermicompostpitathome:

(i) Inthecool,shadedcornerofagarden,digapitabout3feetdeepandspreada2cmthicklayeroflocalsoilatthebottomofthepittopreventseepage.

(ii) Collectsomeredwormsandaddthemtothepitandcoverthislayerwithalayerofgrassorwetnewspaper.

(iii) Putbiodegradablewastesuchasvegetablepeels,plantparts,stale,breadandsooninthepitandspreadtheseevenlyonthelayerofsoil.Addsomepowderedeggshelltohelpthewormsingrindingthewastematerial.

(iv) Sprinklesomewatertokeepthislayerwet. (v) Turnthetoplayerevery2-3daysandafter45daysyouwillfindthatwastehasbeenconverted

intodark-colouredcompost. 4. Waystoreducetheproductionofwaste:

(i) Usepaperandclothforshoppingandstorage. (ii) Useoldnewspaperasbookcoversandpackagingmaterial. (iii) Buyrecycleditemwheneverpossible. (iv) Buyrechargeablebatteriestoreducee-waste. (v) Giveleftoverfoodtoaneedypersonorastrayanimal. 5. Harmfuleffectsofplastics:

(i) Plasticsarethrownintosewersanddraincausingtheblockageofpipes. (ii) Onburning,plasticsreleasemanyharmfulgases. (iii) Itrestrictstheabsorptionofairandwaterbythesoil. (iv) Plasticsthrownhereandtherecanbeeatenbytheanimalswhichresultsintheirdeath. (v) Plasticbagsthatareusedforstoringfoodmaycontainharmfuldyeswhichreactwithfoodand

spoilit. 6. Importanceofrecyclingthewaste:

(i) Recyclinghelpinreusingnon-biodegradablesubstanceslikeplasticswhichotherwisekeeponaccumulatingandpollutetheenvironment.

(ii) Recyclingofpaperhelpsinpreventingthecuttingoftreeswhichsavestheenvironment. (iii) Recyclingisanimportantwaytoconserveourresources.

D. (d) Soakingofpapersinwater (e) Smashingofpapers

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(a) Wiremeshframe (b) Rollerpin (c) DryinginsunE. 1. Aplasticcontainermayhavesomeharmfuldyeswhichreactwithfoodandspoilit.Th us,itisbetter

tostorefoodinmetalcontainer. 2. Kabadiwalascarrypaperwastetotherecyclingfactorieswherethesearerecycledtomakeanew

itemslikepackagingmaterials,recycledpaper,etc.Recyclingofpaperpreventsthecuttingoftrees.Th uskabadiwalasplaysanimportantroleinconservingtheenvironment.

3. Water can be collected in the empty plastic bottles which could become the breeding groundformosquitoes.Ontheotherhand,vegetablewasteisbiodegradableandcanbedecomposedbymicroorganisms.Th us it isnecessary tocrush theemptywaterbottlesbefore throwing them industbinwhilethereissuchneedofdoingthatincaseofvegetablepeels.


1. (a)Leftoverfoodandpaper (b) Paper,Plastic

(c) Metal,Plastic (d) Nitrogen,phosphorusandpotassium

2. Buyfoodinlargepacksandavoidsmallpacking.Th iswillreducethewastegeneratedduetopackaging.

Usefeweramountofdisposableitemssuchaspapernapkinsandglass.

3. Non-biodegradablewastecanbemanagedbyreduce,reuseandrecycletechnique.

4. Th epracticeofseparatingthewasteasbiodegradableandnon-biodegradablewaste.Worksheet 2

1. (c),(e),(b),(a),(f),(d)

2. Burningofpaperandleavesreleasesalotoftoxicgaseswhichisharmfulforus.

3. Selectacool,shadedcornerofyourgarden.Digapitabout3feetdeepandspreada2cmthicklayerofloamysoil/localsoilatthebottomofthepittopreventseepage.Collectsomeredwormsandaddthemtothepitandcoverthislayercontainingwormswithalayerofgrassoranoldclothorwetnewspapers.Th islayerisknownasbedding.Putbiodegradablewastesuchasvegetablepeels,plantparts,stalebread,husk,usedtealeavesandsooninthepitandspreadtheseevenlyonthelayerofsoil.Also,addsomepowderedeggshellsasthesehelpthewormsingrindingthewastematerial.Sprinklesomewatertokeepthislayerwet.Turnthetoplayerevery2-3days.Letthewormsworkforabout40-45days.After45daysorso,observethecontentsofthepit.Youwillfindthatthewastehasbeenconvertedtoadark-colouredcompost.Th isisthemanurethatcanbeusedforplants.

4. Th eendproductofthevermicompostingisknownaswormcasting.

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Answers to Summative Assessment 2

A. 1. (c) 2. (b) 3. (d) 4. (a) 5. (b)B. 1. epidemic 2. 100,10 3. positive,negative 4. maximum,minimum 5. gills,lungsC. 1. Diffusedreflection 2. Famine 3. Humidity 4. Vermicomposting 5. Electricalswitch 6. Demagnetisation 7. LandfillD. 1. SIunitsaremoreaccurateandreliableandcanbeusedbyeveryonetogetthesameresults.Also

theydonotvaryfrompersontopersonandplacetoplace. 2. Bakeliteisahardplasticandaninsulatorwhichprotectsusfromgettinganelectricalshock. 3. Wastemanagement Toavoidpilingupofwasteintheenvironment,itsmanagementisveryessential. Wastecanbemanagedbythefollowingways:

(i) Segregation:Itisimportanttosegregatethewastesothatbiodegradablewastecanbeusedformakingmanurewhilenon-biodegradablewastecanberecycledandusedagain.

(ii) Landfi lls:Largerareasused forbiodegradablewastedisposalarecalled landfills.Garbage isburiedinthegroundinsuchawaythatitdoesnotharmtheenvironment.

(iii) Composting:Incomposting,microorganismsactonbiodegradablewastesandturnthemintomanure.

(iv) Recycling:Ithelpsinreusingofnon-biodegradablesubstanceslikeplasticswhichotherwisewouldkeeponaccumulatingandpollutetheenvironment.

(v) Reduce and reuse: Amount of waste generated by non-biodegradable materials should bereducedbyutilisingthemagain.

4. Rainwater harvesting: Th eprocessofcollectingrainwaterforlateruseiscalledrainwaterharvesting. Twotypesofrainwaterharvestingare:

(i) Rooft op rainwater harvesting: Itisasystemofcollectingrainwaterfromroofsofthehouseor building. It is either stored in a tank or is allowed to seep into the soil to recharge thegroundwater.Th ewatermaycontainssomeimpurities.Th isisaneffectiveandlowcostmethod.

(ii) Surface rainwater harvesting:Th e rainwater which is flowing on the roads and drains iscollectedandisusedtorechargeandrefilldeeppits.Th iswaterseepsinsidethegroundslowlyandreplenishesthewatertable.

5. Electric circuit:Th ecompletepaththatallowscurrenttoflowthroughit,iscalledanelectriccircuitorelectricpath.

ReferfiguregiveninExperiment1onpage162E. 1. (a)Circularandperiodicmotion (b) Rotationalandperiodicmotion (c) Rectilinearmotion (d) Non-periodicmotion (e)Non-periodicmotion 2. Watercycle:

(i) Evaporation and transpiration:Waterpresent intheoceans,rivers, lakes,etc. isconvertedintothevapourformduetotheheatfromsunlight.Alsoplantslosewaterthroughtheprocessoftranspiration.

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(ii) Condensation:The water vapour rises up and condenses to form tiny droplets which oncollectionformacloud.

(iii) Precipitation:Whencloudscannotholdanymorewaterdroplets,theyburstandthedropletscomedownontheearth’ssurfaceintheformofrain,snow,etc.

(iv) Percolation:Water comesback to the earth’s surface, thus completing thewater cycle.Theseepingofwaterintothegroundiscalledpercolation.

ReferFigure15.3onpage174 3. Structure of dry cell:Asthenamesuggests,itcontainsdryorsemi-solidsubstancesinsideit.The

containerofthedrycellismadeupofzinc.Insidethiscontainer,apasteofammoniumchlorideispresentwhichhasthecardboardcontainerhavingpowderedmanganesedioxideandcarboninsideit.Thecardboardcontainerhassomeholesthroughwhichachemicalreactiontakesplacebetweenammoniumchlorideandmanganesedioxide.Arodispresentinsidethemanganesedioxidewhichismadeupofcarbonandhasmetalcap.Thewholethingisthensealedwithonlythemetalcapstickingoutsothatonlythebaseofthedrycellisexposed.

4. Air contains oxygenwhich is needed by humans and animals for breathing and respiration. Itcontainscarbondioxidewhichisrequiredbyplantsforphotosynthesis.Aircontainswatervapourandcarbondioxidewhichtraptheheatofsunlightandthushelpsinmaintainingthetemperatureoftheearth’ssurface.Italsohelpsinseeddispersal.Ithelpsinburningasoxygensupportsburningandalsohelpsingeneratingelectricitythroughwindmills.Alltheseinstancesshowthatairsupportlife.

5. Differentmethodsofmanagingnon-biodegradablewasteare: (i) Reduce: Amountofwastegeneratedshouldbereducedbynotthrowingthosethingsthatcan

beutilisedagain.Forexample:foodcanbeboughtinlargepackswhichwillreducethewastegeneratedduetopackaging.Feweramountofdisposal items likepapernapkins,platesandglassesshouldbeused.

(ii) Reuse: Reusingofmaterialreducestheamountofwastegenerated.Forexample:Oldnewspapercanbeusedasbookcoversandpackagingmaterialwhichreducesthewastageofpaper.Alsozipfoilscanbeusedagainforstoringthingsaftercleaningthemproperly.

(iii) Recycle:Recyclingisanimportantmethodtoconserveourresourcesasithelpsinreusingofnon-biodegradablesubstanceslikeplasticwhichotherwisekeeponaccumulatingandpollutetheenvironment.Recyclingofpaperhelpsinpreventingthecuttingoftreeswhichsavestheenvironment.Itisanimportantwaytoconserveourresources.

F. 1. Thepropertyofleft-rightreversalofanimageformediscalledlateralinversion. 2. Examples:

(i)Theword‘AMBULANCE’iswritteninlaterallyinvertedtextinfrontofvehicle,sothatpersonlookingintherearviewmirrorcanreaditandgivewaytoit.

(ii) Hairpartingthatappearstobeleftwhenviewedinmirrorisseenbyanyotherpersontobeontheright.

3. No,anysurfacethatreflectsbackthelightshowsthelateralinversion.Forexample:clearwaterG. 1. Paperisbiodegradableasitismadefromtrees.Itsrecyclingisimportantasithelpsinpreventing

thecuttingoftrees,thussavingtheenvironment. 2. Thereservoirinadamcollectswaterwhichisusedduringdroughtsandforrecreationalpurposes.

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Model Test Paper 2 100 marks

A. Tick () the correct option. 6 × 1 = 6

1. Whichofthefollowingmotionsisshownbytheneedleofthesewingmachine?

(a) Circularmotion (b) Rotationalmotion

(c) Periodicmotion (d) Non-periodicmotion

2. Whichofthefollowingisaninsulatorofelectricity?

(a) Copper (b) Iron (c) Wood (d) Tapwater

3. Whichofthefollowinganimalsbreathesthroughspiracles?

(a) Birds (b) Mammals (c) Earthworms (d) Cockroaches

4. Whichofthefollowingmethodsisusedtomanagebiodegradablewaste?

(a) Reduce (b) Landfill (c) Reuse (d) Recycle

5. Whichofthefollowingcorrectlydefinesfamine?

(a) Prolongedlackofwater

(b) Prolongedperiodsofheavyrains

(c) Prolongedlackoffood

(d) Overflowingofrivers

6. Whichofthefollowingisatranslucentobject?

(a) Clearwater (b) Air (c) Frostedglass (d) Mirror

B. Fill in the blanks. 6 × 1 = 6

1. Largeareasusedforwastedisposalarecalled________________.

2. _____________doesnotsupportburning.

3. In dry cells, a chemical reaction takes place between __________________ and________________.

4. Th epropertyofleft-rightreversalofanimageiscalled________________.

5. Th elengthofthestretchedouthandiscalled_________________.

6. Adiseaseaffectinganumberofpeopleatthesametimeiscalledan_____________.

C. Give reasons for the following. 4 × 2 = 8

1. Humidityismoreinthecoastalareasascomparedtograsslands.

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2. Seawatercannotbeusedfordrinking.

3. Magnetsshouldbestoredbyusingkeepers.

4. Electricalwiresarecoveredwithplastics.

D. Match the following. 10 × 1 = 10

Column A Column B

Length Beam

Rectilinearpropagationoflight Moistskin

Find directions Filament of bulb

Drycell Metre

Tungsten Cloud

Condensation Unlikepolesofmagnet

Earthworms Magneticcompass

Attraction Battery

Vermicompost Zinc

Combinationofcells Red worms

E. Differentiate between. 5 × 2 = 10

1. Shadowandimage

2. Periodicmotionandnon-periodicmotion

3. Conductorsandinsulators

4. Biodegradablewasteandnon-biodegradablewaste

5. Droughtandflood

F. Answer the following briefly. 10 × 3 = 30

1. Writeanyfivemethodstoreducewaste.

2. Howdothefollowinganimalsbreathe?

(a)Fish (b) Dolphin

(c)Frog (d) Bird

3. Writetheimpactsofflood.

4. Explainthestructureofdrycell.

5. Explaintheworkingofamaglevtrain.

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6. Whatisrectilinearpropagationof light?Alsomentionthedifferencebetweenarayandabeam.

7. Convertthefollowing.

(a)105m=________dm (b) 25389m=_______km

8. Explainthereflectionoflightrayswiththehelpofanexperiment.

9. Whatisrainwaterharvesting?Whatarethetwotypesofrainwaterharvesting?

10. Whatdoyoumeanbyairpollution?Whatareitseffects?

G. Answer the following in detail. 4 × 5 = 20

1. Howcanwemanagenon-biodegradablewaste?

2. Explainwatercycle.

3. Howtomeasurethelengthofalinesegmentusingadivider?

4. Howtomakeavermicompostpit?

H. Look at the given picture and answer the following questions. 2 × 5 = 10

1. Showthedirectionofelectriccurrentinitbyusingarrows.

2. Howdoesitwork?

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Answers to Model Test Paper 1

A. 1. (c) 2. (d) 3. (b) 4. (c) 5. (c) 6. (b)B. 1. parallel 2. Chitin 3. Predator 4. Physical 5. Faster 6. Marasmus 7. Xerophytes 8. WilhelmConardRoentgenC. 1. Someanimalsliveonorwithinotheranimalscalledhostsandobtaintheirfood

directlyfromtheirhostanimals.Suchanimalsareknownasparasites. 2. Afterharvesting,thejutestalksarecuttothegroundandtiedintobundles.Th ese

arethensoakedinwaterforabout20days.Th isprocessiscalledrettingofjute. 3. Th epropertyofmaterialtofloatonwateriscalledflotation. 4. Th ismethodofremovingsaltfromseawateriscalleddesalination. 5. Th eabilitytorespondtostimuliiscalledsensitivity. 6. Th eendsofthebonesarecoveredwithtotough,elastictissuecalledthecartilage. 7. Th e leavespresentonthetreeshavespecial tipscalled 'driptips'whichhelpthe

rainwatertoslideofffromtheirsurface,thusprotectingtheleaffromrotting. 8. Inearthworms,thebodyshapeismaintainedbythefluidpresentinsidethebody

whichiscalledliquidskeletalsystem.D. 1. Dolphin:Th eyhavelungs.Th eyhaveblowholes. Squid:Th eychangetheirbodyshapeaccordinglywhentheymoveinwater.Th ey

alsoreducetheirmovementinwaterbystayingneartheflooroftheocean. 2. Cockroaches can walk, run and fly.Th ey also have an exoskeleton like snails.

Th eir exoskeleton ismadeof ahard substancecalledchitin.Acockroach shedsitsexoskeletonseveraltimesayear.Acockroachalsohasapairofantennaeonitsheadandapairofcercitodetectsignsofdangerfromthefrontorbehindthem.Acockroachhasthreepairsoflegsthathelpitinwalkingandrunningandtwopairsofwingsthathelpitinflyingbutonlyshortdistances.Th eywalkbymovingthreelegsatatime.

3. Photosynthesis: Th emainfunctionoftheleafistopreparefoodfortheplantbytheprocessofphotosynthesis.Th egreen leavesofaplantusewaterandcarbondioxidetopreparefoodinthepresenceofsunlightandchlorophyll.

4. Cold-blooded animals: Animals whose body temperature changes with thetemperatureoftheirsurroundingsarecalledcold-bloodedanimals.Forexample,

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mostofthereptiles,insects,fishesandamphibiansarecold-blooded. Warm-blooded animals:Animalswhosebodytemperatureremainsconstantand

doesnotchangesaccordingtosurroundingsarecalledwarm-bloodedanimals.Forexample,mammalsandbirdsarewarm-blooded.

5. In solids: Theparticlesinsolidsbecomelooseonheatingandtakeupmorespace.Forexample,whileconstructingarailwaytrack,gapsareleftbetweentwotrackssothatsomespaceisavailableforthetrackstoexpandduringsummer.

In liquids: Whenweheata liquid, itsparticlesbecome looseandmovearoundeachotherandtakeupmorespace.

In gases: Theparticlesofagasmovequicklyinalldirectionsonheatingandtakeupmorespace.Forexample,whenwekeepaninflatedballooninsunlightforsometime,wewillobservethattheballoonincreasesinsize.Thisisbecauseitabsorbsheatfromthesunandtheairinsidetheballoonexpandstakingupmorespace.Thechangeinthesizeofballoonisverynegligiblethough.

6. Beingametal,copperislustrous,hard,solid,insolubleinwater,willsinkinwater,conductsheatandelectricity.

7. The stem of the jute plant has a thick bark that has fibres inside it. Jute fibresare naturally glued together by a sticky substance.This sticky substance needstoberemovedtoobtainthefibres. Jute isharvested in itsfloweringstage.Afterharvesting,thejutestalksarecuttothegroundandtiedintobundles.Thesearethensoakedinwaterforabout20days.Thisprocessiscalledrettingofjute.Duringthisprocess,thestalkssoftenandthefibresareseparated.Afterretting,thefibresare separated from the stem, washed, dried and tied into bundles to be sold in market.Thesearethejutefibresthatarethenspunintoyarnandconvertedtojutecloth.

8. Soluble roughage: Itissolubleinwaterandhelpsinbloodcirculation.Examplesofsolubleroughageareapple,peachandrice.

Insoluble roughage: Itisnotsolubleinwater.Examplesofinsolubleroughagearewholegrain,carrot,cabbageandturnip.Lackofinsolubleroughagecausesstoolstobecomehardanddifficulttopass,leadingtoconstipation.

9. This joint provides back and forth movement similar to the hinge of a door.Examplesareknee,elbowandfingerjoints.

Thisjointallowsthebonestoglideovereachotherandfacilitatesmovementinalldirections.Forexample,jointsinourankleandwrist.

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10. (a) Leavesofsomeplantssuchaspeaaremodifiedintheshapeoftendrilswhichareslender, spring-likestructuresandhelpplants toattach themselves toasupport.Suchplantsaregenerallyclimbers.

(b) Inplantssuchascactus,theleavesarereducedtospinestopreventthelossofwaterbytranspiration.

(c) Leavesofcertainplantsgetmodifiedtoformspinestoprotecttheplant.E. 1. Th e process of transfer of pollen grains

fromananthertoastigmaofeitherthesamefloweror of anotherflowerof thesame kind is called pollination. Th istransfercouldbebroughtaboutbywind,water,insectsorman.Th epollengrainsaretransferredtothestigmaoftheflowerand reach the ovary through the style.Th iscausesaseriesofchangesthatresultinthedevelopmentoftheovaryintoafruitandtheovuleschangeintoseeds.

2. Biotic component: Itisthelivingcomponentoftheenvironmentthatconsistsofplantsandanimals.Bioticmeans‘living’.Itisalsocalledthebiologicalenvironment.

Abiotic component: It is the non-living part of the environment that includesair, water (moisture), sun, soil and temperature. It is also called the physicalenvironment.

Allabioticcomponentsoftheenvironmentaffectdifferentbioticcomponentstoalargeextent.Forexample,ifplantsdonotgetadequateamountofsunlight,thentheymay die as they cannot carry out the process of photosynthesis. Animalsdependonplantsforfoodandtheyalsodependontheenvironmentforair,waterandsunlight.Animalsneedadequateamountofsunlightandtemperaturerangetosurviveandifthereisamajorchangeinthisbalancethentheywillbebadlyaffected.So,aproper interactionandbalancebetweenbioticandabiotic factorsof the environment is needed for life to continue. A group of interdependentorganismsthatliveinthesameregionandinteractwithoneanotherformsabioticcommunity.Itincludesplants,animalsandmicroorganisms.

3. Materials required:Beaker,wiregauze,burner,tripodstandandsaltsolution Procedure: Adjustthebeakercontainingsaltsolutiononthetripodstandandwiregauze.Heatthesolutionwiththehelpofaburner.Continueheatingthebeakertillthewaterfromthesolutionevaporates.

Observation:Th ewaterevaporates,leavingthesaltbehindinthebeaker. 4. Adaptations in animals:Avarietyofanimalsarefoundingrasslands.Th eanimal

thathuntsandkillsotheranimalsiscalledapredatorandtheanimalthatishunted

Anther

(A) Self-pollinati on (B) Cross-pollinati on

Pollen grains

Sti gma

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and killed by some other animal is called the prey. For example, consider thefollowingfoodchain.

Plants Deer Lion Inthegivenfoodchain,thedeeristhepreyandthelionisthepredator. Th egolden

brown furof the lionhelps it toblendwith thebackground so that theanimalcannotbelocatedeasilyfromadistance.Someanimalshavepowerfulhindlimbsthathelpthemtorunveryfasttocatchtheirprey.Herbivoreshavestrong,flatandbroadteethtochewthehardgrassofthehabitat.Someanimalssuchasthedeerrunveryfasttoescapethepredators.Ithasverystronglegmuscles.

5. Th eforelimbsofthebirdsaremodifiedaswingsthathelpthemtofly.Th eyusetheirhindlimbs(legs)towalk,runandhop.Th especificfeaturesofthebirdswhichhelpthemtoflyareasfollows.Hollowandlightbonestoreducetheirbodyweight,Strong,enlargedbreastbonethatprovidesasurfaceforattachmentofflightmuscleswhichenablesthemtofly.Streamlinedbodyalsohelpstoreducetheresistanceofairwhileflying.Powerfulchestmuscleshelpthemflaptheirwingsduringflight.

Movement of wings upwards and backwards is termed as the upstroke movement.

Movement of wings downwards and forwards is termed as the downstroke movement.

F. 1. (a) Burningofcoalisanirreversibleandchemicalchange. (b) Burningofcandleisaphysicalandchemicalchange. (c) Bothareirreversiblechanges.Butburningofcoalisachemicalchangewhile

burningofcandleisphysicalandchemicalchangeaswell. 2. (a) Evaporationandcondensation (b) Water converts into steam on heating is called evaporation while steam

convertsbackintowateroncoolingiscalledcondensation. (c) Inwatercycle,bothevaporationandcondensationcanbeseen.

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Answers to Model Test Paper 2

A. 1. (c) 2. (c) 3. (d) 4. (b) 5. (c) 6. (c)B. (a) Landfills (b) Nitrogen (c) Ammoniumchlorideandmanganesedioxide (d)Lateralinversion (e) Handspan (f) EpidemicC. 1. Incoastalareas,theamountofwatervapoursismoreintheairwhichresultsin

morehumidity. 2. Seawatercontainsalotofimpuritieswhichmakesitunfitfordrinking. 3. Topreventthemfromgettingdemagnetised,magnetsarestoredbyusingkeepers. 4. Electricalwiresaremadeofmetalswhicharegoodconductorsofelectricity,soto

coverthemplasticisusedwhichisaninsulatorofelectricity.D.

Column A Column BLength MetreRectilinearpropagationoflight BeamFind directions MagneticcompassDrycell ZincTungsten Filament of bulbCondensation CloudEarthworms MoistskinAttraction UnlikepolesofmagnetVermicompost Red wormsCombinationofcells Battery

E. (a) Shadow Image Ashadowisalwaysblackincolour. Animagehasthecolouroftheobject. Ashadowgivesonlytheoutlineof Animagegivesthedetailsaswellasthe

theobject. outlineoftheobject. Ashadowisformedwhenlightfrom Animageisformedwhenlightfromthe

asourceisblockedbyanopaque objectreachesoureyesafterreflection.object.

Ashadowdoesnotundergolateral Animageundergoeslateralinversion. inversion.

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(b)There are somemotions that are repeated after a regular interval of time. Suchmotions are called periodicmotions or repetitivemotions; for example, a childswingingonaswingandthemovementofaneedleinasewingmachine.

Therearecertainmotionsthatarerepetitivebutnotperiodic.Thisisbecausethesemotionsdonotoccurafterafixedintervaloftime.Suchamotionthatdoesnotrepeat itself at regular intervals or does not repeat at all is called non-periodicmotion.Forexample,acarmovingonaroad,abirdflyingintheskyandchildrenplayinginapark.

3. Therearemanymaterialsthatallowcurrenttopassthroughthem.Thesematerialsarecalledconductorsofelectricity.Metalssuchascopper,silver,ironandsteelareexamplesofconductors.

Materials that do not allow electric current to pass through them are calledinsulatorsorpoorconductorsofelectricity.Examplesofinsulatorsareair,wood,stoneandporcelain.

4. Biodegradablewaste is thewaste that canbe brokendownor decomposed intosimpler formsby tinyorganismscalledmicroorganismspresent in thesoil.Thisincludesleftoverfood,paper,humanwaste,husk,kitchenwasteandwood.

Non-biodegradablewaste isthewastethatcannotbeacteduponbymicroorganismsand thus cannot be decomposed into simpler forms.This type of waste keepsaccumulatingintheenvironment.Thiswasteincludesmetal,plastic,glass,pencilcellsandbatteries.

5. Droughtisaconditionthatoccurswhenanareareceiveslessornorainfallforalongperiod.

Prolongedperiodsofheavyrainsinanareacanresultinaconditioncalledflood. F. 1. Wecannotstoptheproductionofwastecompletelybutwecansurelyminimiseits

generation.Wecanfollowcertainpracticestoreducethegenerationofwaste. •Usepaperandclothbagsforshopping,storageandotherpurposes. •Useoldnewspapersasbookcoversandforpacking. •Giveleftoverfoodtoaneedypersonortoastrayanimal. •Buyrecycleditemswheneverpossible.

•Usebothsidesofapaperbeforethrowingitinthedustbin.

2. Animal Breathingorgani. Fish Gillsii. Dolphin Lungsiii. Frog Moistskin(inwater),lungs(onland)iv. Bird Lungs

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3. •Floodscauselossoflifeandproperty. • Severewatercontaminationoccursduetothedamageofsewagedisposalfacilities

anddeathofhumansandanimals. • Floodscausewaterlogging,resultinginthespreadofdiseasessuchastyphoid,

cholera,HepatitisAandyellowfever.Disease-causinggermsgrowandmultiplyinwaterloggedconditionsandaffectthousandsofpeople.Adiseaseaffectinganumberofpeopleatthesametimeiscalledanepidemic.

• Floodsleadtosoilerosion. • Floodsdamageagriculturalfields,leadingtoreducedcropyield. 4. Asthenamesuggests,adrycellcontainsdryorsemi-solidsubstancesinsideit. •Container: It ismadeupofzinc. Inside thiscontainer,apasteofammonium

chlorideispresentwhichhasacardboardcontainerhavingpowderedmanganesedioxideandcarboninsideit.Thecardboardcontainerhassomeholesthroughwhich a chemical reaction takes place between ammonium chloride andmanganesedioxide.

•Rod:Arodispresentinsidethemanganesedioxide.Thisrodisusuallymadeupofcarbonandhasametalcap.Thewholethingisthensealedwithonlythemetalcapstickingoutsothatonlythebaseofthedrycellisexposed.

Itisthistipofthemetalcapwhichiscalledthepositiveterminal.Similarly,thebaseofthezinccaniscalledthenegativeterminal.Electriccurrentcanbeconsideredto‘flowin’fromoneterminaland‘flowout’fromtheother.Ifthetipofthemetalcapandthebaseofthezinccanareconnectedbyametalwire,currentwillflow throughit.

5. Ahigh-techapplicationofmagnetsisinthemaglevtrainsderivedfrommagneticlevitation.Theyworkontheprincipleofmagneticattractionandrepulsion.Findoutmoreaboutthesetrainsandprepareareportonthis.

6. Thepropertyoflighttotravelinastraightlineiscalledtherectilinearpropagationoflight.Therectilinearpropagationoflightcanbeprovedbyraysandbeamsoflight.Arayisrepresentedbyalinewithanarrowheaddrawntoshowthedirectionofthepropagationoflight.Abeamoflightisbroaderandisacollectionofseveralparallelraysmovinginanorganisedmanner.

7. (a)1m=10dm;So,105m=105×10=1050dm (b)1m=1/1000km;So,25389m=25389/1000=25.389km 8. Materials required: A thermocol sheet, small-sized plane mirror, comb, white

paper sheet and a torch Procedure:Fixthemirrorononesideofthethermocolsheetandthecombonthe

othersideofthesheetinsuchawaythatthereflectingsurfaceofthemirrorfacesthecomb.Spreadthewhitepapersheetbetweenthecombandthemirror.Now

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withthehelpofthetorch,throwlightonthecombsothatitreachesthemirror.Observethepatternofshadowsthatyouobtain.

Observation:Wewillgetanet-likepatternoftheshadowofthecomb.Thelightrayspassthroughthecombandstrikethemirrorandafterstrikingthemirrortheraysgetreflectedandformanet-likepatternonthewhitesheetofpaper.

9. Rainwaterharvestingistheprocessofcollectingrainwaterforlateruse.Rainwatercanbecollectedfromsurfacesonwhichrainfallswhichisthenfilteredandstored.Therearetwomethodsofrainwaterharvesting.

Rooftop rainwater harvesting:Itisasystemofcollectingrainwaterfromroofsofthehouseorbuilding.Itiseitherstoredinatankorisallowedtoseepintothesoiltorechargethegroundwater.Thewatermaycontainsomeimpuritiesandneedstobefilteredbeforeuse.Thisisalowcostandaneffectivemethod.

Surface rainwater harvesting: Therainwaterwhich isflowingon theroadsanddrains is collected and isused to recharge and refill deeppits.Thiswater seepsinsidethegroundslowlyandreplenishesthewatertable.

10.Themixingofundesirablesubstancesinquantitiesthatareharmfultolivingbeingsin air is called pollution. Airpollutioncausesdiseasesof the respiratory systemsuchasasthama,lungcancer,bronchitisandeyediseases.Airpollutionmayalsoleadtoacidrain,whichkillsplantsandaquaticanimals.Itcanleadtochangesintheclimatepatternandcancausewidespreaddestructionofcrops.

G. 1. Non-biodegradablewastesuchasplasticbags,metalsandglasscontainerscannotbebrokendownbytheactionofmicroorganisms.Hence,theirdisposalisaproblem.

Suchwastescanbemanagedbyfollowing3Rs–Reduce,ReuseandRecycle. Reduce: Weshouldreducetheamountofwastegeneratedbynotthrowingthose

thingsthatcanbeutilisedagainandalsobyusingonlywhatwerequire. Reuse: Weshouldfollowthepracticeofreusingthematerialswhereverpossible,so

astoreducetheamountofwastegenerated.Forexample:emptyglassandmetalcontainerscanbeusedtostorekitchenitems,toiletriesandotherthings.

Recycle: Recyclingisanimportantmethodtoconserveourresources.Recyclingmeans processing used materials (waste) to make new useful products. Wastematerialssuchaspaper,plasticandmetalssuchasaluminiumcanscanberecycledandusedagain.

2. Thewater cycle isthecirculationofwaterbetweenEarthandtheatmosphere.Thewater cycle is a significant process tomaintainweather patterns on Earth.Thedifferentstagesinthewatercyclearesummarisedasfollows.

Evaporation: Thewarmth of the sun changeswater in oceans, lakes and other waterbodiesintowatervapour.Waterisalsoevaporatedfromplantsbytheprocessoftranspiration.

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Condensation:Th ewatervapourrisesupandcondensestoformtinydropletsofwater.

Cloud formation:Th esetinydropletscollecttoformclouds.Warmairisabletohold largeramountsof vapour thancoolair.So,whenthiswarmair ladenwithwatervapour,reachestheupperlayeroftheatmosphere,whichisrelativelycooler,itisnolongerabletoholdanymorewatervapour.Th isclusteroftinywaterdropletsfloatinginairiswhatwecallacloud.

Precipitation:Whenthecloudscannotholdanymoredroplets,theyburstandthewaterdropletscomedownonEarth’ssurfaceintheformofrain,snow,sleetorhail.

Percolation:WatercomesbacktoEarth’ssurface,thuscompletingthewatercycle.Th eseepingofwaterintothegroundiscalledinfi ltration or percolation.

Th iscyclicmovementofwaterbetweentheatmosphereandEarththroughvariousprocesses is called the water cycle.

3. Adividerisusedtomeasurethedistancebetweentwopoints.Th edividerisplacedinsuchawaythatthetwoendsofthedividerareonthetwopoints,thelengthofwhichistobemeasured(referPandQinFigure11.15).Th enwithoutdisturbingthedivider,placeitonarulertocheckthelength.

4. Selectacool,shadedcornerofyourgarden.Digapitabout3feetdeepandspreada2cmthicklayerofloamysoil/localsoilatthebottomofthepittopreventseepage.Collectsomeredwormsandaddthemtothepitandcoverthislayercontainingwormswithalayerofgrassoranoldclothorwetnewspapers.Th islayerisknownasbedding.Putbiodegradablewastesuchasvegetablepeels,plantparts,stalebread,husk,usedtealeavesandsooninthepitandspreadtheseevenlyonthelayerofsoil.Also,addsomepowderedeggshellsasthesehelpthewormsingrindingthewastematerial.Sprinklesomewatertokeepthislayerwet.Turnthetoplayerevery2-3days.Letthewormsworkforabout40-45days.After45daysorso,observethecontentsofthepit.Youwillfindthatthewastehasbeenconvertedtoadark-colouredcompost.Th isisthemanurethatcanbeusedforplants.

H. 1.

2. Whenweswitchonthetorch,thecircuitbecomescomplete(closed)andthecurrentflowsthroughit.Th isresultsintheglowingofthetorchbulb.Onswitchingoffthetorch,thecircuitbecomesincomplete(open)andthecurrentdoesnotflow,hence,thetorchdoesnotglow.

The Science Hub - SARASWATI HOUSE Material/978-93-5199-717... · TEACHER’S MANUAL Class 6 Gautam...

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