process

Science as a

Why is the sky blue?

Have you ever wondered why the sky is blue?One of the first science questions that was asked was why is the sky blue?

They first made an observation: The sky is blue.They then asked the question: Why is the sky blue?

What’s Next• Come up with a hypothesis with your neighbor for

the question: why is the sky blue?• Remember: A hypothesis means a testable

statement.• The hypothesis should be in the form of a

statement, (sentence) and the sentence needs to have the ability of being tested

So… Why is the sky blue?

• By: D. Gioffre, Hillsborough Middle School, Hillsborough, NJ 08844

• www.engineeringplanet.rutgers.edu• Pictures from:

– http://teacherweb.com/CT/MadisonMiddleSchool,Trumbull/MrCurry/links1.aspx

What is Scientific Method?

Process which outlines a series of steps used to answer questions.

What are the steps?1. OBSERVATION: Process of gathering information about events or processes.

2. HYPOTHESIS: An educated guess made to answer questions or problems.

3. EXPERIMENT: conducting a carefully controlled search for truth about a hypothesis.

4. CONCLUSION: Analyze results to see if the hypothesis is correct. If not, start over.

designing the

What is Experimental Design?

Includes two groups: Control and Experimental.

control group

Group where all factors are held constant. This is needed

for comparison!

experimental group

Group you are testing where only one factor is changed.

There are three variables within the experimental group:

Dependent, Independent, and Controlled.

dependent variable

The result. It’s what happened. What you measure.

The response.

The ‘’then” part of a hypothesis.

independent variable

The factor you purposely change/manipulate. It’s the

thing you are testing.

The ‘’if” part of a hypothesis.The ‘’if” part of a hypothesis.

controlled variables / constants

all factors which are NOT allowed to change during the

experiment

repeated trials

Experiments must be repeated several times using exactly the same conditions to see if the

results are consistent.

The more times you repeat the experiment, the more VALID your

results are.

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Theory vs. Hypothesis

Theory- A well tested explanation that brings

together many observations. It’s not a law and not absolute

truth!Supported by lots of

experimenting by lots of scientists.

Hypothesis- A proposed scientific explanation for a set

of observations.

Inference vs. Observation

Inference- making a decision based on what you already

know. Ex: We can’t test all the water, but we test a little and

know it’s safe. We infer that all the water is safe to drink.Observation- gathering

information about things in a careful, orderly way. We use our sight and hearing a lot when making observations.

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What are these called?What are these called?

CONSTANTS

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What variable is this?What variable is this?The plant growth that you observe here can be called . . .

The plant growth that you observe here can be called . . . the results (of adding fertilizer) the results (of adding fertilizer) the response (to adding fertilizer) the response (to adding fertilizer) the effects (of adding fertilizer) the effects (of adding fertilizer)

dependent

variable

amt. of wateramt. of water

type of planttype of plant

type of plantertype of plantersize of plantersize of planter

amt. of soilamt. of soil

type of lighttype of light

locationlocation

type of soiltype of soil

What do you do if you want to test the type of soil instead of

fertilizer?

fertilizerfertilizer

Type of soil becomes the IV.Fertilizer becomes a constant.

iviv dvdvconstantsconstants

plant growthplant growth

fertilizerfertilizertype of soiltype of soil

Evaluate the experimental design in

the next two slides.

Dirt: The New Muscle Juice

• Eight year old• Play with trucks• 2 months• Give water

• Eighteen year old• Weight lifting• 6 months• Give Dirt

Which kid will be stronger?

Good experiment?

Questions• What are the controlled variables?• What is the independent variable?• What would be the dependent variable?

forming a

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plant growthplant growthfertilizerfertilizer

constantsconstants

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type of soiltype of soil

type of planttype of plant

type of plantertype of planter

size of plantersize of planter

amt. of soilamt. of soil

type of lighttype of light

locationlocation

If fertilizer

+ verb +

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is added to plants, will improve.

Take 7 minutes to design an experiment using the IVCDV chart to test the strengths of various sunscreen on aliens.

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