Mrs. Silecchia
Vocabulary
A variable is anything that changes.
An independent variable is the one thing you intend to change (vary) in an experiment.
The dependent variable is the variable that changes as a result of the independent variable; what we do
not know and are testing to find out.
A constant is a variable that does not change during the experiment so that it can be used as a base for
comparison.
A control is what we are comparing our experiment to; our “normal” “original” item.
1. Stella thinks that if people are exposed to ultraviolet light then they are more likely to get
skin cancer. Stella designs an experiment wherein sample A consisted of people were
exposed to ultraviolet light and sample B was not.
Control GroupIndependent variable –
Dependent 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 that ¾ of the plants in the 60
degree temperature had been to change colors and only ¼ of the plants in the 80 degree
temperature began to change colors.
Control GroupIndependent variable –
Dependent variable -
3. If poking a skunk will always result in the emission (release) of toxic fumes.
Control GroupIndependent variable –
Dependent variable -
Mrs. Silecchia
Questions #4-7 refer to this experiment:
Suzie Q 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, Suzie observes the plants and measurements.
4. What measurements could Suzy make to determine how different colors of light
affect the growth of plants?
5. What is the independent variable?
6. What is the dependent variable?
7. What are the control variables?
For questions #8-9, refer to the following:
SpongeBob loves to garden and wants to grow lots of pink flowers for his pal Sandy.
He bought a special Flower Power fertilizer to see if will help plants produce more
flowers. He plants two plants of the same size in separate containers with the same
amount of potting soil. He places one plant in a sunny window and waters it every day
with fertilized water. He places the other plant on a shelf in a closet and waters it
with plain water every other day.
8. What did SpongeBob do wrong in this experiment? Explain.
9. How could SpongeBob improve his experiment?