Scientific Method

Preparing for the Science Fair

Testable Questions

• Can be answered through hands-on investigations.

• They are NOT opinion questions or questions that can be answered by doing research in a book or on the internet.

• You must be able to measure the results in some way for it to be considered a testable question.

3 types of testable questions

• 1. The effect question• What is the effect of sunlight on the growth of plants?

• 2. The how does affect question• How does the color of light affect the growth of plants?

• 3. The Which/What and verb question• Which/what paper towel is most absorbent?

Let’s practice identifying testable questions…

What types of apples grow in Michigan?

Not a testable question. It can not be tested through an experiment. You can answer this question with research on the internet or in a book.

How does talking to a plant affect a plants height?

Testable question. It is a How Does Affect question.

Which pill design- tablet, caplet, or capsule- will dissolve faster?

Testable question. It is a Which/What verb question.

Which planet is the most interesting one to study?

Not a testable question. It is an opinion and can not be proved in an experiment.

How does stirring affect the rate that salt dissolves in water?

This is a testable question. It is a How Does affect question.

Writing a Hypothesis

• A hypothesis is a special kind of prediction that forecasts (predicts) how changing one part of an experiment will affect the results.

• It is NOT a guess. It is an informed and well-thought out prediction that requires background information.

• You can also think of it as a cause-effect statement.

• A hypothesis is best written in the “If ______________, then _____________.” format.

• After the “if” is the part the scientist will change on purpose. After the “then” is the result of the change.

• Q: How does the amount of daylight affect how many eggs laid by a chicken?

• H: If the amount of daylight increases, then the chickens will lay more eggs.

Q: How does the amount of leaves on a tree affect how many birds will build nests in it?

H: If a tree has more leaves in it, then birds will be more likely to build a nest in it.

Q: How does the acid level of a lake affect how many fish live there?

H: If a lake has a higher level of acid in it, then fewer fish will live there.

Q: How does the acid level of a lake affect how many fish live there?

H: If a lake has a higher level of acid in it, then fewer fish will live there.

Variables

• Variables are conditions that could affect the outcome of an experiment.

• Think about all of the different things that might affect how well a student does on a test.

• -- their amount of sleep • – how long they studied• –if they’re feeling well • – how well they paid attention in class

• All of those things are variables- they affect how well the student will perform.

What variables can affect the number of fish in a lake?

• Temperature of the water• The quality of the water- pollutants?• What the lake is used for

Discuss with your table group.

• What variables can affect the taste of soda?

There are 3 types of variables. • The independent variable is what you change

on purpose in an experiment. Usually there is only one independent variable in an experiment. Ask yourself “What did I change?”

• The dependent variable is what you measure in an experiment. Ask yourself “What do I observe?”

• The controlled variable is the condition that remains the same in an experiment. Ask yourself “What did I keep the same?”

Q: How does the size of the faucet opening affect the amount of water that flows out of it?

Independent Variable

(What I change)

Dependent Variable

(What I observe)

Controlled Variable

(What I keep the same)

Water faucet opening (closed, half open, fully open)

The amount of water flowing, measured in cups per minute

The faucet

Q: How does the temperature of water affect the rate that sugar dissolves?

Independent Variable

(What I change)

Dependent Variable

(What I observe)

Controlled Variable

(What I keep the same)

The temperature of the water in degrees Fahrenheit.

The amount of sugar that dissolves measured in grams.

Stirring and the type of sugar.