Science Fair How To…

Hypothesis & Variables

Important Terms

• Problem Statement• The question your project will try to answer

• Hypothesis• What you think will happen (research-

based)• Variables

• Parts of the experiment that are changed• Independent Variable (IV)

• What you change• Dependent Variable (DV)

• What you measure• Controlled Variables (constants)

• Everything else in the experiment that stays the same.

Hypothesis

• What you think will happen

• Must contain the Independent Variable (IV) and the Dependent Variable (DV).

• Usually written as an IF, THEN statement.• IF (Independent Variable), THEN (Dependent

Variable).

• Written in the 3rd person• NO: I, me, my, us, you, we, etc…

• Avoid pronouns: • NO: it, they, I, etc…

Hypothesis Example

Problem Statement:

How does the amount of sunlight a strawberry plant receives affect how many berries the strawberry plant will produce?

If the strawberry plants receive 14hrs of sunlight, then the strawberry plant will produce more berries than the strawberry plants that receive 12hrs or 16hrs of sunlight.

Which hypothesis is written the best?

A. I think the double stuffed Oreo will be preferred by 7th graders over the regular Oreo and the triple double Oreo.

B. If the 7th graders are given 3 types of Oreos, then the double stuffed Oreo will be preferred over the regular Oreo and the triple double Oreo.

C. If the students are given 3 types of Oreos, then they will prefer the double stuffed Oreo over the other Oreos.

I think t

he double stuffe...

If the 7th

graders

are giv.

.

If the st

udents are

given ...

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Controlled Variables (CVs or Constants)

• This is everything else in the experiment that stays the same…

• In order for your experiment to be valid and a fair test, everything except the IV must stay exactly the same!

• There cannot be any differences or you cannot say that the IV caused the DV to occur.

The Whole Strawberry Example

Problem Statement:How does the amount of sunlight a strawberry plant receives affect how many berries the strawberry plant will produce?

Hypothesis:If the strawberry plants receive 14hrs of sunlight, then the strawberry plant will produce more berries than the strawberry plants that receive 12hrs or 16hrs of sunlight.

Independent Variable: • Amount of sunlight (in

hours) each plant receives in a day.

Dependent Variable:• Number of berries

producedControlled Variables

(constants):• Type/size of plant• Type/amount of water• Type/amount of soil• Type/size of container• Location in the sun• Etc…

Which is a controlled variable (constant) for the problem statement below:

Do 7th graders consume more regular oreos, double stuffed oreos, or triple double oreos?

A. The plate the oreos are served on

B. The type of oreosC. The number of oreos consumed

The plate the ore

os are ...

The type of o

reos

The number of o

reos c

o...

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Which is NOT a controlled variable for the following question?

Who can see the farthest: 6th graders, 7th graders, or 8th graders?

A. B. C. D.

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A. Brightness of the test areaB. Eye chart usedC. Number of 6th, 7th & 8th gradersD. Grade level of the students

Things to remember

• Write only in the 3rd person: • NO- I, me, my, we or you.

• Avoid pronouns:• NO: it, they, I, etc…

• Write everything in your Science Fair Logbook.

• You may not begin your actual experiment until all your forms are in, your Research Plan has been reviewed and your teacher has approved it.