Question

what are the variables in this experimental setup?
a. the number of pillbugs is the independent variable, and the substance (sand/cornstarch) is the dependent variable.
b. sand is the independent variable, and cornstarch is the dependent variable
c. time is the independent variable, and the number of pillbugs is the dependent variable.
d. the substance (sand/cornstarch) is the independent variable, and the number of pillbugs is the dependent variable.

Explanation:

In a pillbug preference experiment, the independent variable is the factor being tested (the substance: sand or cornstarch, as it is manipulated by the experimenter). The dependent variable is the measured outcome, which is the number of pillbugs choosing each substance, as it depends on the substance provided. Options A, B, and C misidentify the variables: A reverses them, B incorrectly treats the two substances as independent/dependent, and time is not the test variable here.

Answer:

D. The substance (sand/cornstarch) is the independent variable, and the number of pillbugs is the dependent variable.