Scientific Method WS #3 Identifying Variables
1. Jaylin thinks that if people are exposed to ultraviolet light then they are more likely to get
skin cancer. Jaylin designs an experiment wherein sample A consisted of people who were
exposed to ultraviolet light and sample B was not.
Experimental Group-
Independent variable –
Control GroupDependent variable -
2. Justin B. believes that the temperature lowering during the fall months is what causes the
color of the leaves to change. He set up an experiment wherein he placed some plants in 80
degrees rooms and some in 60 degree rooms. He then observed the color of the leaves for a
total of 1 month. At the end of the month Justin observed the colors of the plant leaves.
Independent variable –
Dependent variable -
Victoria wants to know how different colors of light effect the growth of plants. She
believes that plants can survive the best in white light. She buys 5 ferns of the same
species, which are all approximately the same age and height. She places one in white
light, one in blue light, one in green light, one in red light and one in the closet. All of
the ferns are planted in Miracle-Grow and given 20 mL of water once a
day for 2 weeks. After the two weeks, Victoria observes the plants and measurements.
3. What is the independent variable?
What is the dependent variable?
A comprehension test was given to students after they had studied textbook material
either in silence or with the television turned on.
4. Independent Variable:
5. Dependent Variable:
6. Experimental Group:
7. Control Group:
Try and design an experiment from the following hypothesis.
1. If students drink energy drinks then they are more aggressive in school.
Experiment:
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Independent Variable:
Experimental Group:
Dependent Variable:
Control Group:
How could you determine aggressive behavior? What would you look for?
Hypothesis and Problem Writing
Part I: Write a hypothesis for each of the following problem statements. Identify the dependent and
independent variable for each.
1.
How does the amount of leaves on a tree affect how many birds will build nests in it?
Hypothesis: If ____________________________________________________,
then ____________________________________________________________.
2.
How does the acid level of a lake affect how many fish live there?
Hypothesis: If ____________________________________________________,
then ____________________________________________________________.
Write a problem statement that was being answered by each of the following hypotheses.
3.
If I feed my dog Purina Dog Chow, then he will have more energy.
Problem Statement: