How Are the Inuit Astronauts - Griffith Public Schools · PDF fileHow Are the Inuit &...

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How Are theInuit & Astronauts

Connected?

How Are theInuit & Astronauts

Connected?

Bryan & Cherry Alexander

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To find project ideas and resources, visit in6.msscience.com/unit_project.Projects include:• History Contribute to a class time line of inventions from Chinese rockets to liquid

fuel, radio communications, space suits, and more. 6.1.7, 6.2.5, 6.2.7• Technology Research, design, and construct a simple telescope as you study how

technology has allowed scientists to explore distant space. 6.1.2, 6.1.7• Model Investigate the production of space foods, and present an informational

commercial to the class. 6.2.5, 6.2.6, 6.2.7, 6.2.9Investigating the Sun explores the physical characteristics of the sun andenergy it produces. Design a labeled diagram of our nearest star. 6.1.7,6.2.5, 6.2.7, 6.3.17

For thousands of years, people known as the Inuit have lived in Arctic regions. Inthe early 1900s, an American naturalist spent time among the Inuit in Canada.

The naturalist watched the Inuit preserve fish and meat by freezing them in thecold northern air. Months later, when the people thawed and cooked the food, itwas tender and tasted fresh. Eventually, the naturalist returned to the UnitedStates, perfected a quick-freezing process, and began marketing frozen foods.Later, inventors found a way to remove most of the water from frozen foods. Thisprocess, called freeze-drying, produces a lightweight food that can be stored atroom temperature and doesn’t spoil. Freeze-dried foods are carried by all sorts ofadventurers—including astronauts.

The assessed Indiana objective appears in blue.

(l r)NASA, (bkgd)Bryan & Cherry Alexander

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http://in6.msscience.com/unit_project

44

sections

1 What is science?

2 Science in Action

3 Models in Science

4 Evaluating Scientific ExplanationLab What is the right answer?Lab Identifying Parts of an Investigation

Virtual Lab How is a controlledexperiment performed?

How is science a par tof your everyday life?Scientists studying desert ecosystems inCalifornia wondered how such a dry environ-ment could produce such beautiful, prolificflowers. Scientists began asking questions andperforming investigations.

Write down three examples ofscience in your everyday life.Science Journal

The Nature of Science

Academic Standard—1: Students design investigations. They use computers and other technol-ogy to collect and analyze data; they explain findings and can relate how they conduct investiga-tions to how the scientific enterprise functions as a whole. Students understand that technologyhas allowed humans to do many things, yet it cannot always provide solutions to our needs.

Also covers: Academic Standards 2, 4, 5, 7 (Detailed standards begin on page IN8.)

David Keaton/CORBIS

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Science Make the followingFoldable to help identify whatyou already know, what you

want to know, and what you learned aboutscience.

Fold a vertical sheetof paper from side toside. Make the frontedge about 1/2 inchshorter than the backedge.

Turn lengthwise andfold into thirds.

Unfold and cut only the top layeralong both folds to make three tabs.Label each tab.

Identify Questions Before you read the chap-ter, write what you already know about scienceunder the left tab of your Foldable, and writequestions about what you’d like to know underthe center tab. After you read the chapter, listwhat you learned under the right tab.

STEP 3

STEP 2

STEP 1

Observe How Gravity AcceleratesObjects Gravity is a familiar natural force that keepsyou anchored on Earth, but how does itwork? Scientists learn about gravity andother concepts by asking questions andmaking observations. By observing thingsin action scientists can study nature.Perform the lab below to see how gravityaffects objects.

1. Collect three identical, unsharpenedpencils.

2. Tape two of the pencils together.

3. Hold all the pencils at the same height ashigh as you can. Drop them together andobserve what happens as they fall.

4. Think Critically Did the single pencil fallfaster or slower than the pair? Predict inyour Science Journal what would happenif you taped 30 pencils together anddropped them at the same time as youdropped a single pencil.

Start-Up Activities

Preview this chapter’s contentand activities at in6.msscience.com

Know? Learned?Like to know?

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http://in6.msscience.com

Learning About the WorldWhen you think of a scientist, do you imagine a person in a

laboratory surrounded by charts, graphs, glass bottles, and bub-bling test tubes? It might surprise you to learn that anyone whotries to learn something about the natural world is a scientist.Science is a way of learning more about the natural world.Scientists want to know why, how, or when something occurred.This learning process usually begins by keeping your eyes openand asking questions about what you see. Much of the scientificknowledge we have is very old, but is still being used today. Forexample, the sequence of moon phases has been known for centuries.

Asking Questions Scientists ask many questions. How dothings work? What do things look like? What are they made of?Why does something take place? Science can attempt to answermany questions about the natural world, but some questions can-not be answered by science. Look at the situations in Figure 1.Who should you vote for? What does this poem mean? Who isyour best friend? Questions about art, politics, personal prefer-ence, or morality can’t be answered by science. Science can’t tellyou what is right, wrong, good, or bad.

What is science?

■ Define science and identify ques-tions that science cannot answer.

■ Compare and contrast theoriesand laws.

■ Identify a system and itscomponents.

■ Identify the three main branchesof science.

Science can be used to learn moreabout the world you live in.

Review Vocabularytheory: explanation of things orevents that is based on knowl-edge gained from many observa-tions and experiments

New Vocabulary

• science • life science

• scientific • Earth sciencetheory • physical

• scientific law science

• system • technology

Figure 1 Questionsabout politics, literature,and art cannot be answeredby science.

Standards—6.1.1: Explain that some scientific knowledge … is very old and yet is still applicable today…6.1.2: Give examples of different ways scientists investigate natural phenomena and identify processes all sci-entists use … to make sense of the evidence.

Also covers: 6.1.3, 6.1.4, 6.1.5, 6.1.8, 6.1.9, 6.4.13, 6.7.1 (Detailed standards begin on page IN8.)

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SECTION 1 What is science? 7

Question

Possible outcomes

Oneexplanation

Explanationstill possible

Explanationmodified

Explanationdiscarded

New possibleexplanation

Newinformation

Figure 2 As new informationbecomes available, explanationscan be modified or discarded andnew explanations can be made.

Possible Explanations If learning about your world beginswith asking questions, can science provide answers to thesequestions? Science can answer a question only with the informa-tion available at the time. Any answer is uncertain because peo-ple will never know everything about the world around them.With new scientific knowledge, they might realize that some ofthe old explanations no longer fit the new information. Asshown in Figure 2, some observations might force scientists tolook at old ideas and think of new explanations. Science canonly provide possible explanations.

Why can’t science answer questions with certainty?

Scientific Theories An attempt to explain a patternobserved repeatedly in the natural world is called a scientifictheory. Theories are not simply guesses or someone’s opinions,nor are theories vague ideas. Theories in science must be sup-ported by observations and results from many investigations.They are the best explanations that have been found so far.However, theories can change. As new data become available,scientists evaluate how the new data fit the theory. If enoughnew data do not support the theory, the theory can be changedto fit the new observations better.

Scientific Laws A rule that describes a pattern in nature is ascientific law. For an observation to become a scientific law, itmust be observed repeatedly. The law then stands until someonemakes observations that do not follow the law. A law helps youpredict that an apple dropped from arm’s length will always fallto Earth. The law, however, does not explain why gravity existsor how it works. A law, unlike a theory, does not attempt toexplain why something happens. It simply describes a pattern.

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8 CHAPTER 1 The Nature of Science

Systems in ScienceScientists can study many different things in nature. Some

might study how the human body works or how planets movearound the Sun. Others might study the energy carried in a light-ning bolt. What do all of these things have in common? All ofthem are systems. A system is a collection of structures, cycles,and processes that relate to and interact with each other. Thestructures, cycles, and processes are the parts of a system, just likeyour stomach is one of the structures of your digestive system.

What is a system?

Systems are not found just in science. Your school is a systemwith structures such as the school building, the tables andchairs, you, your teacher, the school bell, your pencil, and manyother things. Figure 3 shows some of these structures. Yourschool day also has cycles. Your daily class schedule and the cal-endar of holidays are examples of cycles. Many processes are atwork during the school day. When you take a test, your teacherhas a process. You might be asked to put your books and papersaway and get out a pencil before the test is distributed. When thetime is over, you are told to put your pencil down and pass yourtest to the front of the room.

Parts of a System Interact In a system, structures, cycles,and processes interact. Your daily schedule influences where yougo and what time you go. The clock shows the teacher when thetest is complete, and you couldn’t complete the test without apencil.

Figure 3 Systems are acollection of structures, cycles,and processes.Infer What systems can youidentify in this classroom?

Classifying Parts of a SystemProcedure Think about how your school’scafeteria is run. Consider thephysical structure of the cafe-teria. How many people runit? Where does the food comefrom? How is it prepared?Where does it go? What otherparts of the cafeteria systemare necessary?

AnalysisClassify the parts of yourschool cafeteria’s system asstructures, cycles,or processes.

Mary Kate Denny/PhotoEdit, Inc.

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Parts of a Whole All systems are made up of other systems.For example, you are part of your school. The human body is asystem—within your body are other systems. Your school is partof a system—district, state, and national. You have your regionalschool district. Your district is part of a statewide school system.Scientists often break down problems by studying just one partof a system. A scientist might want to learn about how construc-tion of buildings affects the ecosystem. Because an ecosystemhas many parts, one scientist might study a particular animal,and another might study the effect of construction on plant life.

The Branches of Science Science often is divided into three main categories, or

branches—life science, Earth science, and physical science. Eachbranch asks questions about different kinds of systems.

Life Science The study of living systems and the ways inwhich they interact is called life science. Life scientists attemptto answer questions like “How do whales navigate the ocean?”and “How do vaccines prevent disease?” Life scientists can studyliving organisms, where they live, and how they interact. DianFossey, Figure 4, was a life scientist who studied gorillas, theirhabitat, and their behaviors.

People who work in the health field know a lot about the lifesciences. Physicians, nurses, physical therapists, dietitians, medicalresearchers, and others focus on the systems of the human body.Some other examples of careers that use life science include biol-ogists, zookeepers, botanists, farmers, and beekeepers.

Figure 4 Over a span of18 years, life scientist Dian Fosseyspent much of her time observingmountain gorillas in Rwanda,Africa. She was able to interactwith them as she learned abouttheir behavior.

Scientific Careers Thetypes of jobs available toscientists are extensive. A chemist may work in apharmaceutical industry toresearch new medicines. Abiologist may work for acollege or university doinggenetic research. A physi-cist may work for a govern-ment agency that issending rockets to Mars.

Indiana Academic

Standard Check

6.7.1: Describe that a system,such as the human body, is com-posed of subsystems.

List three subsystems of thehuman body.

Peter Veit/National Geographic Image Collection

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Figure 5 These volcanologistsare studying the temperature ofthe lava flowing from a volcano.

Earth Science The study of Earth systems and the systems inspace is Earth science. It includes the study of nonliving thingssuch as rocks, soil, clouds, rivers, oceans, planets, stars, meteors,and black holes. Earth science also covers the weather and cli-mate systems that affect Earth. Earth scientists ask questions like“How can an earthquake be detected?” or “Is water found onother planets?” They make maps and investigate how geologicfeatures formed on land and in the oceans. They also use theirknowledge to search for fuels and minerals. Meteorologists studyweather and climate. Geologists study rocks and geologic fea-tures. Figure 5 shows a volcanologist—a person who studies vol-canoes—measuring the temperature of lava.

What do Earth scientists study?

Physical Science The study of matter and energy isphysical science. Matter is anything that takes up space andhas mass. The ability to cause change in matter is energy.Living and nonliving systems are made of matter. Examplesinclude plants, animals, rocks, the atmosphere, and the waterin oceans, lakes, and rivers. Physical science can be dividedinto two general fields—chemistry and physics. Chemistry isthe study of matter and the interactions of matter. Physics isthe study of energy and its ability to change matter. Figure 6shows physical scientists at work.

This chemist is studying the lightemitted by certain compounds.

This physicist is studying light asit travels through optical fibers.

Figure 6 Physical scientistsstudy a wide range of subjects.

10 CHAPTER 1 The Nature of Science(tl)G. Brad Lewis/Stone/Getty Images, (bl)Roger Ball/The Stock Market/CORBIS, (br)Will & Deni McIntyre/Photo Researchers

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Self Check1. Compare and contrast scientific theory and scientific

law. Explain how a scientific theory can change.

2. Explain why science can answer some questions, butnot others.

3. Classify the following statement as a theory or a law:Heating the air in a hot-air balloon causes the balloonto rise.

4. Think Critically Describe the importance of technologyand how it relates to science.

SummaryLearning About the World

• Scientists ask questions to learn how, why, orwhen something occurred.

• A theory is a possible explanation for observa-tions that is supported by many investigations.

• A scientific law describes a pattern but doesnot explain why things happen.

Systems in Science

• A system is composed of structures, cycles,and processes that interact with each other.

The Branches of Science

• Science is divided into three branches—lifescience, Earth science, and physical science.

• Technology is the application of science in oureveryday lives.

5. Infer Scientists ask questions and make observations.What types of questions and observations would youmake if you were a scientist studying schools of fish inthe ocean.

Careers Chemists ask questions such as “Howcan I make plastic stronger?” or “What can I do tomake aspirin more effective?” Physicists mightask other types of questions, such as “How doeslight travel through glass fibers?” or “How canhumans harness the energy of sunlight for theirenergy needs?”

Many careers are based on the physical sci-ences. Physicists and chemists are some obviouscareers. Ultrasound and X-ray technicians work-ing in the medical field study physical science becausethey study the energy in ultrasound or X rays and how itaffects a living system.

Science and Technology Although learningthe answers to scientific questions is important, theseanswers do not help people directly unless they can beapplied in some way. Technology is the practical use ofscience, or applied science, as illustrated in Figure 7. Engineersapply science to develop technology. The study of how to use theenergy of sunlight is science. Using this knowledge to createsolar panels is technology. The study of the behavior of light asit travels through thin, glass, fiber-optic wires is science. The useof optical fibers to transmit information is technology. A scien-tist uses science to study how the skin of a shark repels water.The application of this knowledge to create a material that helpsswimmers slip through the water faster is technology.

Figure 7 Solar-powered carsand the swimsuits worn in theOlympics are examples of technol-ogy—the application of science.

in6.msscience.com/self_check_quiz(t)AFP/CORBIS, (b)Reuters NewMedia, Inc./CORBIS

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Science Skills You know that science involves asking questions, but how

does asking questions lead to learning? Because no single way togain knowledge exists, a scientist doesn’t start with step one,then go to step two, and so on. Instead, scientists have a hugecollection of skills from which to choose. Some of these skillsinclude thinking, observing, predicting, investigating, research-ing, modeling, measuring, analyzing, and inferring. Science alsocan advance with luck and creativity.

Science Methods Investigations often follow a general pat-tern. As illustrated in Figure 8, most investigations begin by see-ing something and then asking a question about what wasobserved. Scientists often perform research by talking with otherscientists. They read books and scientific magazines to learn asmuch as they can about what is already known about their ques-tion. Usually, scientists state a possible explanation for theirobservation. To collect more information, scientists almostalways make more observations. They might build a model ofwhat they study or they might perform investigations. Often,they do both. How might you combine some of these skills in aninvestigation?

■ Identify some skills scientists use.■ Define hypothesis.■ Recognize the difference between

observation and inference.

Science can be used to learn moreabout the world you live in.

Review Vocabularyobservation: a record or descrip-tion of an occurrence or pattern innature

New Vocabulary

• hypothesis • independent

• infer variable

• controlled • dependentexperiment variable

• variable • constant

Science in Action

ObserveQuestion

Collect information

Investigateto learn more

Conclude andcommunicateHypothesize Analyze

Observe

Model

Experiment

Measure

Hypothesissupported

Repeatseveral times

Hypothesis notsupported

Modifyhypothesis

Figure 8 Although there are differ-ent scientific methods for investigatinga specific problem, most investigationsfollow a general pattern.

Standards—6.1.3: Recognize and explain that hypotheses are valuable, even if they turn out not to be true, ifthey lead to fruitful investigations. 6.2.5: Organize information in simple tables and graphs and identify rela-tionships they reveal. Use tables and graphs as examples of evidence...

Also covers: 6.1.2, 6.1.5, 6.2.8 (Detailed standards begin on page IN8.)

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SECTION 2 Science in Action 13

Questioning and Observing Ms. Clark placed a sealed shoebox on the table at the front of the laboratory. Everyone in theclass noticed the box. Within seconds the questions flew.“What’s in the box?” “Why is it there?”

Ms. Clark said she would like the class to see how they usedsome science skills without even realizing it.

“I think that she wants us to find out what’s in it,” Isabellesaid to Marcus.

“Can we touch it?” asked Marcus.“It’s up to you,” Ms. Clark said.Marcus picked up the box and turned it over a few times.“It’s not heavy,” Marcus observed. “Whatever is inside slides

around.” He handed the box to Isabelle.Isabelle shook the box. The class heard the object strike the

sides of the box. With every few shakes, the class heard a metal-lic sound. The box was passed around for each student to makeobservations and write them in his or her Science Journal. Someobservations are shown in Figure 9.

Taking a Guess “I think it’s a pair of scissors,” said Marcus.“Aren’t scissors lighter than this?” asked Isabelle, while shak-

ing the box. “I think it’s a stapler.”“What makes you think so?” asked Ms. Clark.“Well, staplers are small enough to fit inside a shoe box, and

it seems to weigh about the same,” said Isabelle.“We can hear metal when we shake it,” said Enrique.“So, you are guessing that a stapler is in the box?”“Yes,” they agreed.“You just stated a hypothesis,” exclaimed Ms. Clark.“A what?” asked Marcus.

Figure 9 Investigations oftenbegin by making observationsand asking questions.

It's not very heavy.

What's that metal-like

sound? It sounds like a stapler.

Biologist Some natural-ists study the livingworld, using mostly theirobservational skills. Theyobserve animals andplants in their naturalenvironment, taking carenot to disturb the organ-isms they are studying.Make observations oforganisms in a nearbypark or backyard. Recordyour observations in yourScience Journal.

Richard Hutchings

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The Hypothesis “A hypothesis is a reasonableand educated pos-sible explanation based on what you know and what you observe.”

“We know that a stapler is small, it can be heavy, and it ismade of metal,” said Isabelle.

“We observed that what is in the box is small, heavier than apair of scissors, and made of metal,” continued Marcus.

Analyzing Hypotheses “What other possible explanationsfit with what you observed?” asked Ms. Clark.

“Well, it has to be a stapler,” said Enrique.“What if it isn’t?” asked Ms. Clark. “Maybe you’re overlook-

ing explanations because your minds are made up. A good sci-entist keeps an open mind to every idea and explanation. Whatif you learn new information that doesn’t fit with your originalhypothesis? What new information could you gather to verify ordisprove your hypothesis?”

“Do you mean a test or something?” asked Marcus.“I know,” said Enrique, “We could get an empty shoe box

that is the same size as the mystery box and put a stapler in it.Then we could shake it and see whether it feels and sounds thesame.” Enrique’s test is shown in Figure 10.

Making a Prediction “If your hypothesis is correct, whatwould you expect to happen?” asked Ms. Clark.

“Well, it would be about the same weight and it would slidearound a little, just like the other box,” said Enrique.

“It would have that same metallic sound when we shake it,”said Marcus.

“So, you predict that the test box will feel and sound thesame as your mystery box. Go ahead and try it,” said Ms. Clark.

Figure 10 Comparing theknown information with theunknown information can bevaluable even though youcannot see what is inside theclosed box.

Forming a HypothesisProcedure1. Fill a large pot with water.

Place an unopened can ofdiet soda and anunopened can of regularsoda into the pot of waterand observe what each candoes.

2. In your Science Journal,make a list of the possibleexplanations for yourobservation. Select thebest explanation and writea hypothesis.

3. Read the nutritional factson the back of each can andcompare their ingredients.

4. Revise your hypothesisbased on this newinformation.

Analysis1. What did you observe

when you placed the cansin the water?

2. How did the nutritionalinformation on the canschange your hypothesis?

3. Infer why the two cansbehaved differently in the water.

14 CHAPTER 1 The Nature of ScienceRichard Hutchings

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Testing the Hypothesis Ms. Clark gavethe class an empty shoe box that appearedto be identical to the mystery box. Isabellefound a metal stapler. Enrique put the sta-pler in the box and taped the box closed.Marcus shook the box.

“The stapler does slide around but itfeels just a little heavier than what’s insidethe mystery box,” said Marcus. “What doyou think?” he asked Isabelle as he handedher the box.

“It is heavier,” said Isabelle “and as hardas I shake it, I can’t get a metallic sound.What if we find the mass of both boxes?Then we’ll know the exact mass difference between the two.”

Using a balance, as shown in Figure 11, the class found thatthe test box had a mass of 410 g, and the mystery box had a massof 270 g.

Organizing Your Findings “Okay. Now you have some newinformation,” said Ms. Clark. “But before you draw any conclu-sions, let’s organize what we know. Then we’ll have a summaryof our observations and can refer back to them when we aredrawing our conclusions.”

“We could make a chart of our observations in our ScienceJournals,” said Marcus.

“We could compare the observations of the mystery boxwith the observations of the test box,” said Isabelle. The chartthat the class made is shown in Table 1.

Figure 11 Laboratory balancesare used to find the mass of objects.

Table 1 Observation Chart

Questions Mystery Box Our Box

Does it roll or slide? It slides and appears to be flat. It slides and appears to be flat.

Does it make any It makes a metallic sound when it The stapler makes a thudding soundsounds? strikes the sides of the box. when it strikes the sides of the box.

Is the mass evenly No. The object doesn’t No. The mass of the stapler isdistributed in the box? completely fill the box. unevenly distributed.

What is the mass 270 g 410 gof the box?

Indiana Academic

Standard Check

6.2.5: Organize information insimple tables and graphs and iden-tify relationships they reveal . . .

From the table below, howcan you tell that the contents ofthe boxes are different?

Matt Meadows

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Drawing Conclusions“What have you learned from your investigation so far?”

asked Ms. Clark.“The first thing that we learned was that our hypothesis

wasn’t correct,” answered Marcus.“Would you say that your hypothesis was entirely wrong?”

asked Ms. Clark.“The boxes don’t weigh the same, and the box with the sta-

pler doesn’t make the same sound as the mystery box. But therecould be a difference in the kind of stapler in the box. It couldbe a different size or made of different materials.”

“So you infer that the object in the mystery box is not exactlythe same type of stapler, right?” asked Ms. Clark.

“What does infer mean?” asked Isabelle.“To infer something means to draw a conclusion based on

what you observe,” answered Ms. Clark.“So we inferred that the things in the boxes had to be differ-

ent because our observations of the two boxes are dif-ferent,” said Marcus.

“I guess we’re back to where we started,” saidEnrique.“We still don’t know what’s in the mystery box.”

“Do you know more than you did before youstarted?” asked Ms. Clark.

“We eliminated one possibility,” Isabelle added.“Yes. We inferred that it’s not a stapler, at least not

like the one in the test box,” said Marcus.“So even if your observations don’t support your

hypothesis, you know more than you did when youstarted,” said Ms. Clark.

Continuing to Learn “So when do we get to openthe box and see what it is?” asked Marcus.

“Let me ask you this,” said Ms. Clark. “Do you thinkscientists always get a chance to look inside to see if theyare right?”

“If they are studying something too big or too smallto see, I guess they can’t,” replied Isabelle.“What do theydo in those cases?”

“As you learned, your first hypothesis might not besupported by your investigation. Instead of giving up, you continue to gather information by making more observations, making new hypotheses, and byinvestigating further. Some scientists have spent life-times researching their questions. Science takespatience and persistence,” said Ms. Clark.

Figure 12 Observations can beused to draw inferences.Infer Looking at these photos, inferwhat has taken place.

Indiana Academic

Standard Check

6.1.3: Recognize and explain thathypotheses are valuable, even ifthey turn out not to be true, if theylead to fruitful investigations.

Why are observations thatdon’t support the hypothesis valuable?

Icon Images

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Communicating Your Findings It is not unusualfor one scientist to continue the work of another or totry to duplicate the work of another scientist. It isimportant for scientists to communicate to othersnot only the results of the investigation, but also themethods by which the investigation was done.Scientists often publish reports in journals, books,and on the Internet to show other scientists the workthat was completed. They also might attend meetingswhere they make speeches about their work.

Like the science-fair student in Figure 13 demon-strates, an important part of doing science is the abil-ity to communicate methods and results to others.

Why do scientists share information?

Figure 13 Presentations are one way peoplein science communicate their findings.

SEASONAL TEMPERATURES Suppose you were given the average temperatures in a city for thefour seasons over a three-year period: spring 1997 was 11°C; summer 1997 was 25°C; fall1997 was 5°C; winter 1997 was �5°C; spring 1998 was 9°C; summer 1998 was 36°C; fall1998 was 10°C; winter 1998 was �3°C; spring 1999 was 10°C; summer 1999 was 30°C; fall1999 was 9°C; and winter 1999 was �2°C. How can you tell in which of the years eachseason had its coldest average?

Solution

This is what you know:

This is what you need tofind out:

This is the procedureyou need to use:

Check your answer:

Temperatures were: 1997: 11°C, 25°C, 5°C, �5°C

1998: 9°C, 36°C, 10°C, �3°C

1999: 10°C, 30°C, 9°C, �2°C

Which of the years each season had its coldest temperature?

● Create a table with rows for seasons and columnsfor the years.

● Insert the values you were given.

The four coldest seasons were spring 1998, summer1997, fall 1997, and winter 1997.

Make a Data Table

Use your table to find out which season had the greatest difference in temperatures over thethree years from 1997 through 1999.

For more practice, visitin6.msscience.com/math_practice

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http://in6.msscience.com/math_practice

Figure 14 The 400-m race isan example of a controlled experi-ment. The distance, track material,and wind speed are constants. Therunners’ abilities and their finishtimes are varied.

ExperimentsDifferent types of questions call for different types of inves-

tigations. Ms. Clark’s class made many observations about theirmystery box and about their test box. They wanted to knowwhat was inside. To answer their question, building a model—the test box—was an effective way to learn more about the mys-tery box. Some questions ask about the effects of one factor onanother. One way to investigate these kinds of questions is bydoing a controlled experiment. A controlled experimentinvolves changing one factor and observing its effect on anotherwhile keeping all other factors constant.

Variables and Constants Imagine a race in which thelengths of the lanes vary. Some lanes are 102 m long, some are98 m long, and a few are 100 m long. When the first runnercrosses the finish line, is he or she the fastest? Not necessarily.The lanes in the race have different lengths.

Variables are factors that can be changed in an experiment.Reliable experiments, like the race shown in Figure 14, attempt tochange one variable and observe the effect of this change onanother variable. The variable that is changed in an experiment iscalled the independent variable. The dependent variable changesas a result of a change in the independent variable. It usually is thedependent variable that is observed in an experiment. Scientistsattempt to keep all other variables constant—or unchanged.

The variables that are not changed in an experiment arecalled constants. Examples of constants in the race include trackmaterial, wind speed, and distance. This way it is easier to deter-mine exactly which variable is responsible for the runners’ fin-ish times. In this race, the runners’ abilities were varied. Therunners’ finish times were observed.

18

Topic: Scientific MethodVisit in6.msscience.com for Weblinks to information about thescientific method.

Activity Identify the three vari-ables needed in every experimentand summarize the differencesbetween them.

Rud

i Von

Brie

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Laboratory SafetyIn your science class, you will perform many types of inves-

tigations. However, performing scientific investigations involvesmore than just following specific steps. You also must learn howto keep yourself and those around you safe by obeying the safetysymbol warnings, shown in Figure 16.

In a Laboratory When scientists work in a laboratory, asshown in Figure 15, they take many safety precautions.

The most important safety advice in a science lab is to thinkbefore you act. Always check with your teacher several times inthe planning stage of any investigation. Also make sure youknow the location of safety equipment in the laboratory roomand how to use this equipment, including the eyewashes, ther-mal mitts, and fire extinguisher.

Good safety habits include the following suggestions. Beforeconducting any investigation, find and follow all safety symbolslisted in your investigation. You always should wear an apron andgoggles to protect yourself from chemicals, flames, and pointedobjects. Keep goggles on until activity, cleanup, and handwashingare complete. Always slant test tubes away from yourself and oth-ers when heating them. Never eat, drink, or apply makeup in thelab. Report all accidents and injuries to your teacher and alwayswash your hands after working with lab materials.

In the Field Investigations also take place outside the lab, instreams, farm fields, and other places. Scientists must followsafety regulations there, as well, such as wearing eye goggles andany other special safety equipment that is needed. Never reachinto holes or under rocks. Always wash your hands after you’vefinished your field work.

Figure 15 Safety is themost important aspect ofany investigation.

Eye Safety

Clothing Protection

Disposal

Biological

Extreme Temperature

Sharp Object

Fume

Irritant

Toxic

Animal Safety

Flammable

Electrical

Chemical

Open Flame

Handwashing

Figure 16 Safety symbols arepresent on nearly every investiga-tion you will do this year.List the safety symbols that shouldbe on the lab the student is prepar-ing to do in Figure 15.

Bob Daemmrich

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Self Check1. Explain the difference between an inference and an

observation.

2. Explain the differences between independent anddependent variables.

3. Think Critically A classroom investigation lists bleachas an ingredient. Bleach can irritate your skin, damageyour eyes, and stain your clothes. What safety symbolsshould be listed with this investigation? Explain.

SummaryScience Skills

• The scientific method was developed to helpscientists investigate their questions.

• Hypotheses are possible explanations for whysomething occurs.

Drawing Conclusions

• Scientists communicate with one another toshare important information.

Experiments

• Controlled experiments test the effect of onefactor on another.

Laboratory Safety

• Safety precautions must be followed whenconducting any investigation.

Why have safety rules? Doing science in the class labora-tory or in the field can be much more interesting than readingabout it. However, safety rules must be strictly followed, so thatthe possibility of an accident greatly decreases. However, youcan’t predict when something will go wrong.

Think of a person taking a trip in a car. Most of the time whensomeone drives somewhere in a vehicle, an accident, like the oneshown in Figure 17, does not occur. But to be safe, drivers andpassengers always should wear safety belts. Likewise, you alwaysshould wear and use appropriate safety gear in the lab—whetheryou are conducting an investigation or just observing. The mostimportant aspect of any investigation is to conduct it safely.

Figure 17 Accidents are notplanned. Safety precautions mustbe followed to prevent injury.

4. Describe the different types of safety equipmentfound in a scientific laboratory. From your list, whichequipment should you use when working with a flammable liquid in the lab?

in6.msscience.com/self_check_quizGlasheen Graphics/Index Stock

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http://in6.msscience.com/self_check_quiz

SECTION 3 Models in Science 21

Why are models necessary? Just as you can take many different paths in an investigation,

you can test a hypothesis in many different ways. Ms. Clark’sclass tested their hypothesis by building a model of the mysterybox. A model is one way to test a hypothesis. In science, a modelis any representation of an object or an event used as a tool forunderstanding the natural world.

Models can help you visualize, or picture in your mind, some-thing that is difficult to see or understand. Ms. Clark’s class made amodel because they couldn’t see the item inside the box. Modelscan be of things that are too small or too big to see. They also canbe of things that can’t be seen because they don’t exist anymore orthey haven’t been created yet. Models also can show events thatoccur too slowly or too quickly to see. Figure 18 shows differentkinds of models.

Models in Science

■ Describe various types of models.■ Discuss limitations of models.

Models can be used to help under-stand difficult concepts.

Review Vocabularyscientific method: processes sci-entists use to collect informationand answer questions

New Vocabulary

• model

Figure 18 Modelshelp scientists visualizeand study complexthings and things thatcan’t be seen.

Cell model

Dinosaur model

Solar system model

Prototype model

Standard—6.7.2: Use models to illustrate processes that happen too slowly, too quickly, or on too small ascale to observe directly, or are too vast to be changed deliberately, or are potentially dangerous.

Also covers: 6.1.2, 6.1.6, 6.5.5 (Detailed standards begin on page IN8.)

(cw from top)David Young-Wolff/PhotoEdit, Inc., Donald C. Johnson/The Stock Market/CORBIS, John Bavosi/Science Photo Library/Photo Researchers, A. Ramey/PhotoEdit, Inc.

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Types of Models Most models fall into three basic types—physical models,

computer models, and idea models. Depending on the reasonthat a model is needed, scientists can choose to use one or morethan one type of model.

Physical Models Models that you can see and touch arecalled physical models. Examples include things such as a table-top solar system, a globe of Earth, a replica of the inside of a cell,or a gumdrop-toothpick model of a chemical compound.Models show how parts relate to one another. They also can beused to show how things appear when they change position orhow they react when an outside force acts on them.

Computer Models Computer models are built using com-puter software. You can’t touch them, but you can view them ona computer screen. Some computer models can model eventsthat take a long time or take place too quickly to see. For exam-ple, a computer can model the movement of large plates in theEarth and might help predict earthquakes.

Computers also can model motions and positions of thingsthat would take hours or days to calculate by hand or even usinga calculator. They can also predict the effect of different systemsor forces. Figure 19 shows how computer models are used byscientists to help predict the weather based on the motion of aircurrents in the atmosphere.

What do computer models do?

Figure 19 A weather map is acomputer model showing weatherpatterns over large areas. Scientistscan use this information to predictthe weather and to alert people topotentially dangerous weather onthe way.

Topic: Topographic MapsVisit in6.msscience.com for Weblinks to information abouttopographic maps.

Activity List some of the differ-ent features found on topographicmaps and explain their importancewhen reading and interpretingmaps.

CORBIS/PictureQuest

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Idea Models Some models are ideas or concepts that describehow someone thinks about something in the natural world.Albert Einstein is famous for his theory of relativity, whichinvolves the relationship between matter and energy. One of themost famous models Einstein used for this theory is the mathe-matical equation E � mc2. This explains that mass, m, can bechanged into energy, E. Einstein’s idea models never could bebuilt as physical models, because they are basically ideas.

Making Models The process of making a model is something like a sketch

artist at work, as shown in Figure 20. The sketch artist attemptsto draw a picture from the description given by someone. Themore detailed the description is, the better the picture will be.Like a scientist who studies data from many sources, the sketchartist can make a sketch based on more than one person’s obser-vation. The final sketch isn’t a photograph, but if the informa-tion is accurate, the sketch should look realistic. Scientificmodels are made much the same way. The more information ascientist gathers, the more accurate the model will be. Theprocess of constructing a model of King Tutankhamun, wholived more than 3,000 years ago, is shown in Figure 21.

How are sketches like specific models?

Using Models When you think of a model, you might think of a model air-

plane or a model of a building. Not all models are for scientificpurposes. You use models, and you might not realize it.Drawings, maps, recipes, and globes are all examples of models.

Figure 20 Models can be cre-ated using various types of tools.

Thinking Like a ScientistProcedure1. Pour 15 mL of water into a

test tube.2. Slowly pour 5 mL of veg-

etable oil into the testtube.

3. Add two drops of food col-oring and observe the liq-uid for 5 min.

Analysis1. Record your observations

of the test tube’s contentsbefore and after the oil andthe food coloring wereadded to it.

2. Infer a scientific explana-tion for your observations.

Todd Gipstein/CORBIS

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Figure 21


More than 3,000 years ago, KingTutankhamun ruled over Egypt. Hisreign was a short one, and he died

when he was just 18. In 1922, his mummifiedbody was discovered, and in 1983 scientistsrecreated the face of this most famous ofEgyptian kings. Some of the steps inbuilding the model are shown here.

This is the mostfamiliar image ofthe face of KingTut—the goldfunerary mask thatwas found coveringhis skeletal face.

When this model of King Tut’sface was completed, the long-deadruler seemed to come to life.

D

First, a scientist used measurements andX rays to create a cast ofthe young king’s skull.Depth markers (in red)were then glued ontothe skull to indicate thelikely thickness of mus-cle and other tissue.

A

Next, thefeatures weresculpted. Here,eyelids are fash-ioned over inlaidprosthetic, orartificial, eyes.

C

Clay wasapplied to fill inthe area betweenthe markers.

B

VISUALIZING THE MODELING OF KING TUT

(tr)Richard Nowitz/Words & Pictures/PictureQuest, (bl)Michael O'Brian/Mud Island, Inc., (others)Betty Pat Gatliff

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Models Communicate Some models are used to communi-cate observations and ideas to other people. Often, it is easier tocommunicate ideas you have by making a model instead of writ-ing your ideas in words. This way others can visualize them, too.

Models Test Predictions Some models are used to test pre-dictions. Ms. Clark’s class predicted that a box with a stapler init would have characteristics similar to their mystery box. To testthis prediction, the class made a model. Automobile and air-plane engineers use wind tunnels to test predictions about howair will interact with their products.

Models Save Time, Money, and Lives Other models areused because working with and testing a model can be safer andless expensive than using the real thing. For example, the crash-test dummies shown in Figure 22 are used in place of peoplewhen testing the effects of automobile crashes. To help trainastronaunts in the conditions they will encounter in space,NASA has built a special airplane. This airplane flies in an arcthat creates the condition of freefall for 20 to 25 seconds.Making several trips in the airplane is easier, safer, and lessexpensive than making a trip into space.

Figure 22 Models are a safe andrelatively inexpensive way to testideas.

Crash-test dummies areused to test vehicles with-out putting people indanger.

Wind tunnels can be used to test new airplane designs or changes made to existing airplanes.

Astronauts train in aspecial aircraft thatmodels the conditionsof space.

Indiana Academic

Standard Check

6.7.2: Use models to illustrateprocesses that . . . are potentiallydangerous.

Give one example of a modelused to minimize potential dan-gers of the real item or situation.

(l)Carol Anne Petrachenko/CORBIS, (c)Jim Sugar Photography/CORBIS, (r)Tom Wurl/Stock Boston/PictureQuest

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Self Check1. Infer what types of models can be used to model

weather. How are they used to predict weather patterns?

2. Explain how models are used in science.

3. Describe how consumer product testing services use mod-els to ensure the safety of the final products produced.

4. Describe the advantages and limitations of the threetypes of models.

5. Think Critically Explain why some models are betterthan others for certain situations. Give one example.

SummaryWhy are models necessary?

• Scientists develop models to help them visu-alize complex concepts.

Types of Models

• There are three types of models—physicalmodels, computer models, and idea models.

Making Models

• The more information you have when creatinga model, the more accurate the model will be.

Using Models

• Models are used to convey important infor-mation such as maps and schedules.

Limitations of Models

• Models can be changed over time as newinformation becomes available.

6. Use Proportions On a map of a state, the scale showsthat 1 cm is approximately 5 km. If the distancebetween two cities is 1.7 cm on the map, how manykilometers separate them?

Limitations of Models The solar system is too large to be

viewed all at once, so models are madeto understand it. Many years ago, scien-tists thought that Earth was the centerof the universe and the sky was a blan-ket that covered the planet.

Later, through observation, it wasdiscovered that the objects you see inthe sky are the Sun, the Moon, stars,and other planets. This new modelexplained the solar system differently.Earth was still the center, but everythingelse orbited it as shown in Figure 23.

Models Change Still later, through more observation, it wasdiscovered that the Sun is the center of the solar system. Earth,along with the other planets, orbits the Sun. In addition, it wasdiscovered that other planets also have moons that orbit them.A new model was developed to show this.

Earlier models of the solar system were not meant to be mis-leading. Scientists made the best models they could with the infor-mation they had. More importantly, their models gave futurescientists information to build upon. Models are not necessarilyperfect, but they provide a visual tool to learn from.

An early model of thesolar system had Earthin the center with every-thing revolving around it.

Figure 23 The model ofEarth’s solar system changedas new information wasgathered.

Later on, a new model had the Sunin the center with everythingrevolving around it.

in6.msscience.com/self_check_quiz(l)Stock Montage, (r)North Wind Picture Archives

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Believe it or not?Look at the photo in Figure 24. Do you believe what you see?

Do you believe everything you read or hear? Think of somethingthat someone told you that you didn’t believe. Why didn’t youbelieve it? Chances are you looked at the facts you were given anddecided that there wasn’t enough proof to make you believe it.What you did was evaluate, or judge the reliability of what youheard. When you hear a statement, you ask the question “How doyou know?” If you decide that what you are told is reliable, thenyou believe it. If it seems unreliable, then you don’t believe it.

Critical Thinking When you evaluate something, you usecritical thinking. Critical thinking means combining what youalready know with the new facts that you are given to decide ifyou should agree with something. You can evaluate an explana-tion by breaking it down into two parts. First you can look atand evaluate the observations. Based upon what you know, arethe observations accurate? Then you can evaluate the infer-ences—or conclusions made about the observations. Do theconclusions made from the observations make sense?

Evaluating ScientificExplanation

■ Evaluate scientific explanations.■ Evaluate promotional claims.

Evaluating scientific claims can helpyou make better decisions.

Review Vocabularyprediction: an educated guess asto what is going to happen basedon observation

New Vocabulary

• critical thinking

• data

Figure 24 In science, observa-tions and inferences are not alwaysagreed upon by everyone. Compare Do you see the samethings your classmates see in thisphoto?

27

Standard—6.2.8: Analyze and interpret a given set of findings, demonstrating that there may be more than onegood way to do so.

Also covers: 6.1.1, 6.1.5, 6.2.5, 6.5.2 (Detailed standards begin on page IN8.)

Digital Art/CORBIS

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Evaluating the Data A scientific investigation always contains observations—

often called data. Data are gathered during a scientific investiga-tion and can be recorded in the form of descriptions, tables,graphs, or drawings. When evaluating a scientific claim, youmight first look to see whether any data are given. You should becautious about believing any claim that is not supported by data.

Are the data specific? The data given to back up a claimshould be specific. That means they need to be exact. What ifyour friend tells you that many people like pizza more thanthey like hamburgers? What else do you need to know beforeyou agree with your friend? You might want to hear about aspecific number of people rather than unspecific words likemany and more. You might want to know how many peoplelike pizza more than hamburgers. How many people wereasked about which kind of food they liked more? When you aregiven specific data, a statement is more reliable and you aremore likely to believe it. An example of data in the form of a

frequency table is shown in Table 2. A frequencytable shows how many times types of data occur.Scientists must back up their scientific state-ments with specific data.

Take Good Notes Scientists must take thor-ough notes at the time of an investigation, as thescientists shown in Figure 25 are doing. Importantdetails can be forgotten if you wait several hoursor days before you write down your observations.It is also important for you to write down everyobservation, including ones that you don’t expect.Often, great discoveries are made when somethingunexpected happens in an investigation.

Figure 25 These scientists arewriting down their observationsduring their investigation ratherthan waiting until they are backon land.Draw Conclusions Do you thinkthis will increase or decrease thereliability of their data?

Table 2 Favorite Foods

People's Prefe Tally ency

Pepperonipizza

Hamburgerswith ketchup

28

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tock

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Your Science Journal During this course, you will be keep-ing a science journal. You will write down what you do and seeduring your investigations. Your observations should be detailedenough that another person could read what you wrote andrepeat the investigation exactly as you performed it. Instead ofwriting “the stuff changed color,” you might say “the clear liquidturned to bright red when I added a drop of food coloring.”Detailed observations written down during an investigation aremore reliable than sketchy observations written from memory.Practice your observation skills by describing what you see inFigure 26.

Can the data be repeated? If your friend told you hecould hit a baseball 100 m, but couldn’t do it when you werearound, you probably wouldn’t believe him. Scientists alsorequire repeatable evidence. When a scientist describes an inves-tigation, as shown in Figure 27, other scientists should be ableto do the investigation and get the same results. The results mustbe repeatable. When evaluating scientific data, look to seewhether other scientists have repeated the data. If not, the datamight not be reliable.

Evaluating the ConclusionsWhen you think about a conclusion that someone has made,

you can ask yourself two questions. First, does the conclusionmake sense? Second, are there any other possible explanations?Suppose you hear on the radio that your school will be runningon a two-hour delay in the morning because of snow. You lookoutside. The roads are clear of snow. Does the conclusion thatsnow is the cause for the delay make sense? What else couldcause the delay? Maybe it is too foggy or icy for the buses to run.Maybe there is a problem with the school building. The originalconclusion is not reliable unless the other possible explanationsare proven unlikely.

Figure 26 Detailed observationsare important in order to get reli-able data.Observe Use ten descriptive wordsto describe what you see happeningin this photo.

Figure 27 Working togetheris an important part of science.Several scientists must repeat anexperiment and obtain the sameresults before data are consideredreliable.

29

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Self Check1. Describe why it is important that scientific experiments

be repeated.

2. List what types of scientific claims should be verified.

3. Explain how vague claims in advertising can bemisleading.

4. Think Critically An advertisement on a food packageclaims it contains Glistain, a safe taste enhancer. Makea list of ten questions you would ask when evaluatingthis claim.

Summary Believe it or not?

• By combining what you already know withnew information as it becomes available, youcan decide whether something is fact or fiction.

• Explanations should be evaluated by lookingat both the observations and the conclusionsthe explanation is based on.

Evaluating the Data

• It is important to take thorough notes duringany investigation.

Evaluating the Conclusions

• In order for a conclusion to be reliable, it mustmake sense.

Evaluating Promotional Materials

• Independent laboratories test products inorder to provide more reliable results.

5. Classify Watch three television commercials andread three magazine advertisements. Record theclaims that each advertisement made. Classify eachclaim as being vague, misleading, reliable, and/or scientific.

Evaluating PromotionalMaterials

Scientific processes are not used only inthe laboratory. Suppose you saw an adver-tisement in the newspaper like the one inFigure 28. What would you think? First,you might ask, “Does this make sense?” Itseems unbelievable. You would probablywant to hear some of the scientific datasupporting the claim before you wouldbelieve it. How was this claim tested? How isthe amount of wrinkling in skin measured?You might also want to know if an inde-pendent laboratory repeated the results. Anindependent laboratory is one that is notrelated in any way to the company that isselling the product or service. It has nothing

to gain from the sales of the product. Results from an independ-ent laboratory usually are more reliable than results from a lab-oratory paid by the selling company. Advertising materials aredesigned to get you to buy a product or service. It is importantthat you carefully evaluate advertising claims and the data thatsupport them before making a quick decision to spend yourmoney.

Figure 28 All material shouldbe read with an analytical mind.

in6.msscience.com/self_check_quiz

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Scientists sometimes develop more than oneexplanation for observations. Can more thanone explanation be correct? Do scientific expla-nations depend on judgment?

Real-World QuestionCan more than one explanation apply to thesame observation?

Goals■ Make a hypothesis to explain an

observation. ■ Construct a model to support your

hypothesis. ■ Refine your model based on testing.

Materialscardboard mailing tubes length of rope*empty shoe boxes scissors*Alternate materials

Safety Precautions

WARNING: Be careful when punching holes withsharp tools.

Procedure1. You will be shown a cardboard tube with

four ropes coming out of it, one longer thanthe others. Your teacher will show you thatwhen any of the three short ropes—A, C, orD—are pulled, the longer rope, B, getsshorter. Pulling on rope B returns the otherropes to their original lengths.

2. Make a hypothesis as to how the teacher’smodel works.

3. Sketch a model of a tube with ropes basedon your hypothesis. Using a cardboard tubeand two lengths of rope, build a model

according to your design. Test your modelby pulling each of the ropes. If it does notperform as planned, modify your hypothesisand your model to make it work like yourteacher’s model.

Conclude and Apply1. Compare your model with those made by

others in your class.

2. Can more than one design give the sameresult? Can more than one explanationapply to the same observation? Explain.

What is the right answer?

LAB 31

Indiana Academic

Standard Check

6.2.8: Analyze and interpret agiven set of findings, demonstrat-ing that there may be more thanone good way to do so.

Without opening the tube,can you tell which model is exactlylike your teacher’s model? Explain.

Amanita Pictures

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Identifying Parts of an Investigation


Real-World QuestionScience investigations contain many parts.How can you identify the various parts ofan investigation? In addition to vari-ables and constants, many experi-ments contain a control. A control isone test, or trial, where everythingis held constant. A scientist com-pares the control trial to the othertrials. What are the various parts ofan experiment to test which fertilizerhelps a plant grow best?

Procedure1. Read the description of the fertilizer experiment.

2. List factors that remained constant in the experiment.

3. Identify any variables in the experiment.

4. Identify the control in the experiment.

5. Identify one possible hypothesis that the gardener could havetested in her investigation.

6. Describe how the gardener went about testing her hypothesisusing different types of fertilizers.

7. Graph the data that the gardener col-lected in a line graph.

A gardener was interested in helping herplants grow faster. When she went tothe nursery, she found three fertilizersavailable for her plants. One of those fer-tilizers, fertilizer A, was recommended toher. However, she decided to conduct atest to determine which of the three fer-tilizers, if any, helped her plants growfastest. The gardener planted four seeds,each in a separate pot. She used thesame type of pot and the same type ofsoil in each pot. She fertilized one seed

Goals■ Identify parts of an

experiment.■ Identify constants,

variables, and controlsin the experiment.

■ Graph the results ofthe experiment anddraw appropriate con-clusions.

Materialsdescription of fertilizer

experiment

(t)Aaron Haupt, (b)Matt Meadows

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Analyze Your Data1. Describe the results indicated by your graph. What part of an investigation

have you just done?

2. Infer Based on the results in the table and your graph, which fertilizer do youthink the gardener should use if she wants her plants to grow the fastest? Whatpart of an investigation have you just done?

3. Define Suppose the gardener told a friend who also grows these plants abouther results. What is this an example of?

Conclude and Apply1. Interpret Data Suppose fertilizer B is much more expensive than fertilizers A

and C. Would this affect which fertilizer you think the gardener should buy?Why or why not?

2. Explain Does every researcher need the same hypothesis for an experiment?What is a second possible hypothesis for this experiment (different from theone you wrote in step 5 in the Proceduresection)?

3. Explain if the gardener conducted an adequatetest of her hypothesis. Compare your conclusions with those of

other students in your class. For more help,

refer to the Science Skill Handbook.

LAB 33

with fertilizer A, one with fertilizer B,and one with fertilizer C. She did notfertilize the fourth seed. She placedthe four pots near one another in hergarden. She made sure to give eachplant the same amount of water eachday. She measured the height of theplants each week and recorded herdata. After eight weeks of carefulobservation and record keeping, shehad the following table of data.

Plant Height (cm)

er

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Is your family doctora man or a woman?To your great-

grandparents, such aquestion would likelyhave seemed odd.Why? Because 100years ago, womenweren’t encouragedto study science asthey are today. Butthat does notmean that therewere no female scien-tists back in your great-grandparents’ day.Many women managed to overcome great bar-riers and made discoveries that changed theworld.

Maria GoeppertMayer

“To my sur-prise, winningthe prize wasn’thalf as excitingas doing thework itself.That was thefun—seeing itwork out.”Dr. MariaGoeppert

Mayer won the Nobel Prize in Physics in 1963for her work on the structure of an atom.Her model greatly increased humanunderstanding of atoms, which make upall forms of matter.

Rita Levi-MontalciniIn 1986, Dr. Rita Levi-Montalcini was

awarded the Nobel Prize in Medicine forher discovery of growth factors. Growth fac-tors regulate the growth of cells and organsin the body. Because of her work, doctors arebetter able to understand why tumors formand wounds heal.

RosalynSussman Yalow

“The world can-not afford the loss ofthe talents of half itspeople if we are tosolve the many prob-lems which beset us,”Dr. Rosalyn SussmanYalow said upon win-ning the Nobel Prize inMedicine in 1977 for dis-covering a way to measure tiny substances in theblood, such as hormones and drugs.

Her discovery made it possible for doctorsto diagnose problems that they could notdetect before.

Research Visit the link to the right to research some recentfemale Nobel prizewinners in physics, chemistry, and medicine.Write a short biography about their lives. How did their discoveriesimpact their scientific fields or people in general?

For more information, visitin6.msscience.com/time

WomenSciencein

SCIENCEAND

HISTORYSCIENCE

CAN CHANGE THE COURSE OF HISTORY!

(t)Reuters/CORBIS, (bl)UPI/Bettmann/CORBIS, (br)TIME

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http://in6.msscience.com/time

Copy and complete the following concept map.

What is science?

1. Science is a way of learning more about thenatural world. It can provide possible expla-nations for why and how things happen.

2. Systems are made up of structures, cycles,and processes that interact with one another.

Science in Action

1. A hypothesis is a possible explanation basedon what you know and what you observe.

2. It is important to always follow laboratorysafety symbols and to wear and use appro-priate gear during an experiment.

Models in Science

1. Models are a graphic representation of anobject or an event used to communicateideas; test predictions; and save time,money, and lives.

Evaluating ScientificExplanation

1. Reliable data are specific and repeatable byother scientists.

2. In order for a conclusion to be consideredreliable, it must make sense and be themost likely explanation.

CHAPTER STUDY GUIDE 35in6.msscience.com/interactive_tutor

Science

Earth systemsand the systems

in space

can be divided into

which is thestudy of

whenapplied is

Living systems and the ways in which

they interact

which is thestudy of

which is divided into

Matter andinteractions

of matter

Energy and its ability to

change matter

which is the study ofwhich is the study of

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Explain the relationship between the words inthe following sets.

1. hypothesis—scientific theory

2. constant—variable

3. science—technology

4. science—system

5. Earth science—physical science

6. critical thinking—infer

7. scientific law—observation

8. model—system

9. controlled experiment—variable

10. scientific theory—scientific law

Choose the word or phrase that best answers thequestion.

11. What does it mean to make an inference?A) make observationsB) draw a conclusionC) replaceD) test

12. Which of the following CANNOT protectyou from splashing acid?A) goggles C) fire extinguisherB) apron D) gloves

13. If the results from your investigation donot support your hypothesis, what shouldyou do?A) Should not do anything.B) Repeat the investigation until it agrees

with the hypothesis.C) Modify your hypothesis.D) Change your data to fit your hypothesis.

14. Which of the following is NOT an exam-ple of a scientific hypothesis?A) Earthquakes happen because of stresses

along continental plates.B) Some animals can detect ultrasound

frequencies caused by earthquakes.C) Paintings are prettier than sculptures.D) Lava takes different forms depending

on how it cools.

15. Using a computer to make a three-dimensional picture of a building isa type of which of the following?A) model C) constantB) hypothesis D) variable

16. Which of the following increases the relia-bility of a scientific explanation?A) vague statementsB) notes taken after an investigationC) repeatable dataD) several likely explanations

17. Which is an example of technology?A) a squirt bottle C) a catB) a poem D) physical science

18. What explains something that takes placein the natural world?A) scientific law C) scientific theoryB) technology D) experiments

19. An airplane model is an example of whattype of model?A) physical C) ideaB) computer D) mental

36 CHAPTER REVIEW

constant p. 18controlled experiment p. 18critical thinking p. 27data p. 28dependent variable p. 18Earth science p. 10hypothesis p. 14independent variable p. 18infer p. 16

life science p. 9model p. 21physical science p. 10science p. 6scientific law p. 7scientific theory p. 7system p. 8technology p. 11variable p. 18

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CHAPTER REVIEW 37

20. Draw Conclusions When scientists study howwell new medicines work, one group ofpatients receives the medicine while a sec-ond group does not. Why?

21. Predict How is usinga rock hammeran example oftechnology?

22. Compare and ContrastHow are scientific theories andscientific laws similar? How arethey different?

Use the table below to answer question 23.

23. Use Tables Mohs hardness scale measureshow easily an object can be scratched. Thehigher the number, the harder the mate-rial is. Use the table above to identifywhich material is the hardest and which isthe softest.

24. Make Operational Definitions How does ascientific law differ from a state law?Give some examples of both types oflaws.

25. Infer Why it is important to recordand measure data accurately duringan experiment?

26. Predict the quickest way to get to school inthe morning. List some ways you couldtest your prediction.

27. Hypothesize Using a basketball and a ten-nis ball, make a hypothesis about thenumber of times each ball will bouncewhen it hits the ground. Drop each ballfrom shoulder height five times, record-ing the number of bounces in a table.Which ball bounced more? Make ahypothesis to explain why.

28. Observe Pour some water in a small dishand sprinkle some pepper on top. Noticehow the pepper floats on the water. Nowadd a few drops of liquid soap to thewater. Write down your observations asyou watch what happens to the pepper.

Hardness

O ale

co

di

fin

gl

qu

st

Use the illustration below to answer question 29.

29. Use Proportions The map above shows thedistance between two points. The scale showsthat 1 cm is approximately 1.05 km. What isthe approximate distance between Point Aand Point B?

San Francisco

TreasureTreasureIslandI

y Bridge

Key: 1 cm = 1.05 km

in6.msscience.com/chapter_reviewTim Courlas

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The assessed Indiana standard

appears above the question.

Record your answers on the answer sheetprovided by your teacher or on a sheet of paper.

A model of the solar system is shown below.

1. What type of model is this?

A computer

B idea

C physical

D realistic

2. Which is NOT shown in the model above?

A the Moon

B the planets

C the stars

D the Sun

3. Which is combining what you already knowwith new facts to evaluate an explanation?

A communicating results

B critical thinking

C hypothesizing

D inferring

4. What are the variables that do NOT changein an experiment?

A constants

B dependent variables

C independent variables

D inferences

5. The photo below shows a scientist observ-ing mountain gorillas.

In the photo, which science skill is the sci-entist most likely using?

A analyzing graphs and tables

B communicating results

C forming a hypothesis

D investigating to learn more

Mars JupiterEarth

Venus

Moon

Sun

Mercury

SaturnUranus

Neptune

Pluto

38 INDIANA

IndianaIndianachapter chapter

6.7.2

6.7.2

6.1.5

Practice Remember that test-taking skills can improve withpractice. If possible, take at least one practice test andfamiliarize yourself with the test format and instructions.

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ISTEP+ PRACTICE 39

6. A scientist directly changes how many vari-ables in a controlled experiment?

A all

B none

C one

D two

7. Which question can science NOT answer?

A Why do leaves change colors?

B Why do squirrels hibernate in the winter?

C Where do waves in the ocean form?

D What is the most exciting book?

8. You are designing an experiment to test theclaims in the ad shown below.

Which experiment method is most reliable?

A testing the same amount of cream onskin with different amounts of wrinkling

B testing different amounts of cream onskin with similar amounts of wrinkling

C testing the same amount of cream onskin with similar amounts of wrinkling

D testing different amounts of cream onskin with different amounts of wrinkling

9. You want to learn whether plants growfaster if there is music playing in theirenvironment. List four possible constantsin your experiment. What variable wouldyou change?

10. Construct a frequency table from the fol-lowing data. Make two observations aboutthe data. 15 students prefer cold pizza forlunch; 10 students enjoy peanut butter withjelly; 3 students bring ham and cheese; and5 students eat hot dogs and chips.

11. Describe the three major categories intowhich science is classified. Which branchesof science would be most important to anenvironmental engineer? Why?

12. The photo below shows a student workingin a lab.

Using the photo, identify three safety pre-cautions this student should take.

in6.msscience.com/ISTEP_practice

ISTEP+ PracticeISTEP+ Practice

6.2.9

6.2.5

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