One tank of goldfish is fed the normal amount of food once a day, a second tank is fed twice a day, and a third tank four times a day during a six week study. What is the independent variable, the dependent variable, the control group, and the constant?

The independent variable is the fish feed that is being fed to the fish. This is because this variable is what is being varied to affect the dependent variable. In this case, the dependent variable is fishes - more specifically, maybe their weight. The constant variable is the fish tank size and conditions. This variable is kept constant in the experiment and does not change because changing it would alter the experiment. The control group - that is used to compare the results with those of the treatments - is the tank being fed normally.