Scientific Method

What is Scientific Method?• Scientific method is the process used to

answer questions and solve problems about the world around us.

There are 6 steps to scientific method

these steps are followed to test ideas, but serve only as a guide.

Sometimes,

several of the steps are used

while others are not needed

when solving a particular problem.

Or, the steps might be

performed in a different order.

Step #1

• You recognize a problem and ask a question.

• Decide what you want to know

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Step #2

• Gather information– Previous knowledge– Make observations– Do research

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Observation vs. Inference

• Observation is what you notice *

Ex. The dog is barking

• Inference draws a conclusion or makes an explanation *

Ex. The dog is hungry

An inference is usually based on previous knowledge.

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Observation

Observation: when studying something, describe only facts that you can see, touch, smell and hear. You are not making any guesses. THIS IS NOT AN OPINION!!

Ohh… This liquid is green and it is leaking from a brown can. I also smell it.

Inference

Inference: using your observations to make a guess about an object or an outcome

THIS CAN BE A SCIENTIFIC

OPINION

Based on my observations, I think that this can is old and is leaking a toxic substance.

Group Practice

• Please make some observations and inferences about the following picture.

Individual Practice• On your note packet, please write down 2 observations and 2

inferences about the following picture.

Step #3

Form a Hypothesis• A hypothesis is a prediction that can be

tested.

• It is often written as “If” “then” statements

“If I do this (independent variable )

then (dependent variable)

will happen”

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Step #4

Testing your hypothesis

Testing your hypothesis involves an observational study OR an experiment.

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Observational Study

• Does not involve an experiment. You observe without changing the variables. The scientist observes and record his/her observations.

An Experiment

An experiment has a control, variables,

and a constant.

Controls and Variables

• A control is a standard with which to compare the results of your experiment.**

• Variables are factors in an experiment.**

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Types of Variables

• Independent Variable is the variable you purposely change. This is what is being tested. **

• Dependent Variable is the variable that changes in response to that change. It is the factor that is observed and measured.**

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Controlled Variable or Constant

A constant is all of the other variables in the experiment that should not change…they always stay the same.**

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Which soda, when combined with mentos, explodes the highest?

• Independent variable:

What are we testing?

Type of soda• Dependent variable:

What will we measure?

Height of explosion• Controlled variables/Constants:

What will stay the same in all tests?

Number of mentos, type of mentos, amount of soda

Step #5

Analyze your data*** Data is the information collected in

the experiment.

* The information is usually written into an easily readable chart called a data table

* Data can be analyzed in many ways

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Graphs to analyze Data

Graphs are commonly used to analyze data. Data is often organized into graphs which can help show relationships between variables.

Graphs show relationships between variables **

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How to graph

• Be sure to title your graph…the title represents what the graph is all about.

The title should be labeled at the top of the graph.

The “Y” axis should be labeled with the Dependent Variable.

• The “X” axis should be labeled with the Independent Variable.

Title of the graphEx. “Effect of water on plant growth”

Independent Variable (X-axis)Ex. Amount of Water (ml)

Dep

ende

nt V

aria

ble

(Y-a

xis)

Ex.

Pla

nt G

row

th (

mm

)

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Graph relationshipsDirect Relationship

Increasing X results in an increase in Y

Ex. As time studying increases, test scores increase.

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Graph Relationship

• Indirect Relationship

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Increasing X results in Y decreasing **

Ex. As time increases, eyesight ability decreases

Graph RelationshipConstant Relationship

If X is increased, Y stays the same (unaffected) ** Ex. As time spent reading Shakespeare is increased,

the students test score on the Scientific Method remains the same

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Graph Relationship

• Cyclic

A repeating patternEx. As time of day is increased, amount of light

increases, then decreases.

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.

Step #6

Draw Conclusions

Explain your results from the experiment.Did it support your hypothesis??? If not, why not?

Includes: ** -Restate problem and hypothesis -Inferences -Data to back up inferences -Possible problems with experiment design -What you would do next?

(change hypothesis and retest?, study another aspect of the problem?)

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What makes a good experiment?

Only one independent variable! **

The rest must remain constant.

Ex. You can’t test the effect of light and water on plant growth at the same time.

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A good experiment

Your experiment is well thought out and planned.

You are able to tell how you will change the independent variable.

And how you will measure the dependent variable

A good experiment

The constants should remain unchanged

• Has multiple trials – Repeating the experiment eliminates error. **

• Has large sample sizes– If we test more “subjects,” we can be more

sure the results are real. **

A good experiment**Write this

YIPPIEEEEEEEEEE

Lets do an experiment!!!