Question

what are the variables in this experimental setup?
a. sand is the independent variable, and cornstarch is the dependent variable.

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

c. time is the independent variable, and the number of pillbugs is the dependent variable.

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

Explanation:

In an experimental setup, the independent variable is what is manipulated, and the dependent variable is what is measured (depends on the independent variable). Here, the substance (sand or cornstarch) is manipulated (independent variable), and the number of pillbugs (their response, like attraction/repulsion) would be measured (dependent variable). Option A is wrong as sand and cornstarch are not independent - dependent in that way. Option C: Time isn't the manipulated factor here (the substance is). Option D reverses independent and dependent (substance is manipulated, not dependent on pillbugs). So B is correct.

Answer:

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