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# Experiments - Controls and Variables (Grade 8)

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## Experiments - Controls and Variables

1.
A factor in an experiment that can change is                .
1. an observation
2. a variable
3. a control
4. a hypothesis
2.
This is used in an experiment to show that the results of an experiment are actually a result of the condition being tested:
1. the independent variable
2. the control
3. hypothesis
4. the dependent variable
3.
A(n)                      is a variable representing the value being manipulated or changed.
1. hypothesis
2. constant
3. independent variable
4. control group
5. dependent variable
6. meter
4.
This is the factor in an experiment can change if other factors are changed:
1. the independent variable
2. the constant
3. hypothesis
4. the dependent variable
5.
If Sam was completing an experiment to determine if fertilizer makes a plant grow better than not using fertilizer, which of the following would be the best step?
1. Place one plant in the sun and the other in a closet
2. Water one plant every day and the other plant every other day
3. Keep both plants on top of a cabinet
4. Use a tomato plant and a bean plant
6.
I am trying to clean my bathroom shower because it has mold on the bottom. I was told to use Xtraclean to get it up. I use Xtraclean on half of the bathroom shower and water on the other half. The control is:
1. Water
2. Xtraclean
3. Shower
4. Mold
7.
Why do experiments usually test only one variable at at time?

8.
How does an experimental group differ from a control group?

9.
Mr. Krabs wants to test whether or not his secret ingredient for breath mints will cure the bad breath people get from eating crabby patties. He conducted an experiment on 100 customers. Mr Krabs had 50 customers (Group A) eat a breath mint with his secret ingredient after eating a crabby patty . The other 50 customers (Group B) were given a regular breath mint without the secret ingredient. Both groups were told that they were getting the breath mint and that it would cure their bad breath. Two hours after eating the crabby patties and mints, 30 customers from Group A and 10 customers from Group b reported having better breath than they normally had after eating crabby patties.

Which group is the control group?

What is the independent variable?

What is the dependent variable?

Why do you think 10 people in Group B reported fresher breath?

10.
SpongeBob noticed that his favorite pants were not as clean as they used to be. Sandy told him to try using a new brand of laundry detergent called Clean-O. SpongeBob washed one pair of pants in plain water and another pair in water with the Clean-O detergent. After washing both pairs a total of three times, the pants washed in the Clean-O did not appear to be any cleaner than the pants washed in plain water.

What was the problem SpongeBob wanted to investigate?

What is the independent variable?

What is the dependent variable?

What should Sponge Bob's conclusion be?

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