Scientific Method

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.• Activity carried on by humans that is

designed to discover information about the natural world.

• Organized inquiry into the natural world and its phenomena.

• Science is about gaining a deeper and often useful understanding of the world.

•Science is not exact or perfect. From time to time, scientific explanations may change as new data is presented. •The process of testing and fine-tuning theories never endsnever ends as scientists try to gain new insights into old problems

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What is the goal of Science?

To develop an understanding of the natural universe

which is free of human bias.

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Scientific Method

Scientist use the scientific method to solve problems.

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What is the Scientific Method?•An organized set of steps

used to solve a problem.•Is there a certain number of sets?

•NO!NO!•It is simply a logical way to solve a problem.

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•Can you form conclusions about something before you make observations?

•NO!

66•Can you form conclusions about something before you test it?•NO!

EXAMPLEEXAMPLE Clip(1) (1) Observation:Observation:

– Something done through the Something done through the five senses.five senses.

““I don’t hit very well I don’t hit very well with my baseball bat.”with my baseball bat.”

(2) (2) State the problem:State the problem: ““I need a bat that will I need a bat that will

allow me to hit better.”allow me to hit better.”

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What is an observation?

???

(3)Form a Hypothesis:“If I use a different bat, then I will hit more home runs.”*Hypothesis must be testable!

(4)Test the Hypothesis through an experiment:

How could I set up this experiment?????

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Performing a Performing a GOODGOOD experiment experiment99

What is a GOOD

experiment?- It truly tests for what it is

supposed to test for.

How can we make sure that our

experiment is a GOOD

experiment?- Follow a

few simple rules.

Rules:Rules:#1. An experiment usually

contains two variables.(1)Independent Variable

(manipulated) What the experimenter...YOU…

changes.(2) Dependent Variable

(responding) What happens because

the IV changes.

Performing a Performing a GOODGOOD experiment experiment1010

Type of bat

More homeruns

Rules:Rules:#2. All experiments need a

control.What is a control??

A control is something to compare the experimental

results to.What’s our control?Our regular bat.

Performing a Performing a GOODGOOD experiment experiment1111

Setting up the Experiment

The The experiment:experiment:

I will hit 100 balls with 4

bats and compare the number of homeruns.

How can I make sure

that the bat is the only factor

affecting the way I hit the

ball?

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How can I make sure

that the bat is the only factor

affecting the way I hit the

ball?

•Ball thrown the same every time.

•Same type/age ball.•Weather the same

every day.•Same number of hits

every day.•Same amount of sleep each night.

•Can you think of any others???

These are called

CONSTANTS.-They are the same in the -They are the same in the experimental group and experimental group and

the control group. -the control group. -They do not changeThey do not change

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Why do we need

Constants?

To make sure we are testing for what we

said we are testing for.

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0102030405060708090

100

1 2 3 4

Bat

Num

ber o

f Hom

erun

s ou

t of 1

00

at b

ats

Regular Bat

Data

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After the Experiment(5)Analyzing the data• “What is the data telling me?”• What did we learn?• I hit more homeruns with bat #3.(6)Draw conclusions.• Was the hypothesis supported?• YES!• What does this data mean for the

future?• -I will use bat #3.

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0102030405060708090

100

1 2 3 4

Bat

Num

ber

of H

omer

uns

out o

f 100

at

bat

s

Regular Bat

•How can we be sure that the results are real?

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What’s a theory?•Scientific Theories are

based on knowledge gained from many

experiments.•NOT A GUESS!

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Clip2121

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OBSERVATIONS:OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.

HYPOTHESIS:HYPOTHESIS: Flies produce maggots.PROCEDURE:PROCEDURE:

Controlled Controlled Variables:Variables:jars, type of meat,location,temperature,timeManipulated Manipulated Variables:Variables:gauze covering thatkeeps flies away from meat

Uncovered jars Covered jars

Several days pass

Maggots appear No maggots appear

Responding Responding Variable:Variable: whether maggots appear

CONCLUSIONCONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.

Redi’s Experiment on Spontaneous Redi’s Experiment on Spontaneous GenerationGeneration

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Observation vs. Observation vs. InferenceInference

•An observationobservation is the information gathered using any of your senses.

•An inferenceinference is an explanation of the data based on facts but not on direct observation.

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Statement Observation InferenceObject A is round and orange.Object A is a basketball.Object C is round and black and white.Object C is larger than Object B.Object B is smooth.Object B is a table-tennis ball.

•Object A is a basketball.•Object B is a table-tennis ball.•Object C is a soccer ball.

Inference vs. ObservationX

XXXX

X

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EOCT EOCT QuestionsQuestions

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When leaving a movie theater, a person notices that the sidewalk is now wet. If the person assumes it rained while watching the movie, the person is making

AA a hypothesis a hypothesisBB an inference an inferenceCC an an observationobservationDD a prediction a prediction

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A student wants to determine the effect of salt on the freezing point of water. A

student adds 200 mL of pure water to three identical containers. To one container, 2 g

of the salt is added; in the second container, 4 g of the salt is added; and in the third container no salt is added. The three containers are placed in the same freezer. The temperature of the water is measured every 10 min for one hour, and the observations are recorded in a data

table. What is the independent variable in this experiment?A the amount of salt

addedB the temperature measuredC the type of salt usedD the type of container used

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