Chapter 1 – Section 1Chapter 1 – Section 1

What is Science?What is Science?

Steps to the Scientific MethodSteps to the Scientific Method

1. Identify Problem or Question1. Identify Problem or Question2. Research and Gather Information2. Research and Gather Information3. Form a Hypothesis3. Form a Hypothesis4. Experiment4. Experiment5. Analyze Data5. Analyze Data6. Draw a Conclusion6. Draw a Conclusion

Identify Problem or QuestionIdentify Problem or Question

Usually developed from a Usually developed from a question you want to answerquestion you want to answer

Use clear termsUse clear terms Identify variables in the questionIdentify variables in the question Ex: Does a certain type of cat Ex: Does a certain type of cat

litter irritate cats’ skin?litter irritate cats’ skin?

Research and Gather Information

Research what is known about topics related to the question (what is cat litter made of?)

Sources might include the internet, magazines, encyclopedias, videos, interviews

Information is gathered before making a hypothesis

Research and Gather Info, con’t

Information can be in the form of observations (ex: the cats are itchy and biting their skin)

Information can be results from other experiments or field studies

It is Time for An It is Time for An Example!Example!

Question: Question: Does acid rain affect plant Does acid rain affect plant growth?growth?

What are some things you could look What are some things you could look up that would relate to our question?up that would relate to our question?

The pH of acid rainThe pH of acid rain

How pH/acid rain affects plantsHow pH/acid rain affects plants

Where acid rain is found on EarthWhere acid rain is found on Earth

Results from other people’s experimentsResults from other people’s experiments

Form a HypothesisForm a HypothesisAn explanation that can be testedAn explanation that can be testedA hypothesis is written in A hypothesis is written in “If-then”“If-then” formatformatShould be very specificShould be very specificEx: If cat litter contains Ex: If cat litter contains deodorant, then it will irritate the deodorant, then it will irritate the cats’ skin.cats’ skin.

It’s Time for an Example!It’s Time for an Example!

Problem: Problem: Does acid rain affect Does acid rain affect the growth of a the growth of a PothosPothos plant? plant?

Write a hypothesis for the problem.Write a hypothesis for the problem.

If acid rain with a pH of 4 is If acid rain with a pH of 4 is sprayed on a sprayed on a PothosPothos plant for plant for three weeks, then the plant three weeks, then the plant growth will be slower than the growth will be slower than the control plants.control plants.

Test the Hypothesis (Experiment)Test the Hypothesis (Experiment)

Test the hypothesis in controlled settingsTest the hypothesis in controlled settings

Can contain only one variable (can test only Can contain only one variable (can test only one characteristic at a time)one characteristic at a time)

Use senses to gather information during Use senses to gather information during experimentexperiment

Experiment, continuedExperiment, continued

Should have one control group that is Should have one control group that is not testednot tested

Control group sets the standard for the Control group sets the standard for the test groups’ results to be compared totest groups’ results to be compared to

example: A group of example: A group of PothosPothos plants plants is not sprayed with acid rain is not sprayed with acid rain

Can have multiple experimental groupsCan have multiple experimental groups

Variables???Variables???

A A variablevariable is a part of the experiment that can is a part of the experiment that can be changed be changed

There are two types of variablesThere are two types of variables

1. Independent variableIndependent variable - the variable you - the variable you control/test (ex: type of cat litter)control/test (ex: type of cat litter)

2. Dependant variableDependant variable - the variable you - the variable you measure (ex: skin irritation)measure (ex: skin irritation)

Time for an Example!Time for an Example!

Problem: Problem: Does acid rain affect plant Does acid rain affect plant growth?growth?

Identify the independent variableIdentify the independent variable

Acid rainAcid rain Identify the dependant variableIdentify the dependant variable

Plant growthPlant growth

Analyze DataAnalyze Data

• Decide Decide which data is importantwhich data is important and and which data is not related to your which data is not related to your hypothesishypothesis

• CreateCreate graphs graphs for your datafor your data

• You should be able to You should be able to recognize errorsrecognize errors made during the experiment which made during the experiment which may affect your datamay affect your data

• Look for Look for patternspatterns in your data in your data

Time for an Example!Time for an Example!

0

5

1 0

1 5

2 0

2 5

3 0

3 5

w e e k 1 w e e k 2 w e e k 3 w e e k 4

c o n t r o l

a c i d r a i n

Draw a ConclusionDraw a Conclusion

You should You should accept or rejectaccept or reject your your hypothesis based on your datahypothesis based on your data

ExplainExplain the the scientific reasonscientific reason for your for your resultsresults

Explains mistakes or poor experimental Explains mistakes or poor experimental designdesign as a reason for unusual data as a reason for unusual data

Based on Based on datadata and and researchresearchLogical answerLogical answer to a question to a question

Time for anTime for an ExampleExample!!

Write a possible Write a possible conclusion for our acid conclusion for our acid rain example.rain example.

The answer is….The answer is….

Plants prefer water that has a neutral pH. Plants prefer water that has a neutral pH. The acid rain has a low pH which means it The acid rain has a low pH which means it would damage cells. Damaged cells will would damage cells. Damaged cells will not grow as quickly. Also, if cells are not grow as quickly. Also, if cells are damaged, they may not divide correctly damaged, they may not divide correctly causing the plant to grow slowly. causing the plant to grow slowly. However, a pH of 4 did not stop all growth, However, a pH of 4 did not stop all growth, it only slowed it. It may take more than 4 it only slowed it. It may take more than 4 weeks to see a real difference in the weeks to see a real difference in the growth of the two groups of plantsgrowth of the two groups of plants

Theory

Explains events using scientific knowledge

Results of many experiments support the theory

Ex: cell theory says all living things are made of cells

Theory, con’t

Theories change over time as more evidence is collected

Theories usually explain why something happens

Laws

A statement about how things work in nature that seems to always be true

Less likely to change than a theory

Ex: Newton’s Universal Law of Gravitation that says all things are attracted to each other by the force of gravity.

Units of Measurement Mass measures the amount of matter in an

object

Measured with a balance

Units are grams (g)

Units of Measurement, con’t

Volume is the amount of space an object takes up

Volume of solids are calculated by l x w x h Volume of liquids are measured with a flask,

graduated cylinder, or beaker Liquid units are liters (L). Solid units are cubic centimeters (cm3)

Units of Measurement, con’t Distance is measured in meters (m) using a

ruler or meterstick.

Time is measured in seconds (s) using a stopwatch.

Weight is the amount of gravity pulling on an object and is measured with a spring scale. The units are Newtons (N)