Question

Calvin and Michelle wanted to test the effects of different household cleansers on the growth of mildew. They selected three identical bathroom tiles to use in their experiment. To one tile, they applied Brand X cleanser. To another, they applied Brand Y cleanser. The third tile did not receive any cleanser. They observed the growth of the mildew over a period of four days. Their results are shown in the table below. Which of the following is a constant, or control in this experiment?

A. the results observed over four days
B. the brand of the cleanser that worked the best
C. the use of identical bathroom tiles
D. the brand of cleanser that didn’t work

Answer 1

A constant, or control in this experiment is C. the use of identical bathroom tiles.

What occurs in this experiment?

In an experiment, a constant is a factor that is kept the same across all groups. This allows the researchers to isolate the effect of the independent variable (the factor they are changing) on the dependent variable (the factor they are measuring).

In this experiment, the independent variable is the type of cleanser used. The dependent variable is the growth of mildew. The use of identical bathroom tiles is a constant because it ensures that any differences in mildew growth are due to the type of cleanser used and not to differences in the tiles themselves.

Therefore, the use of identical bathroom tiles is the constant in this experiment.