what is the independent variable?

Answer 1

In an experiment, the independent variable is the variable that you are testing the effect of, the one that you are actively manipulating (changing) to see what its effect(s) are?

Example: Experiment to test the effect of fertilizer amount of tomato production.

Experiment: Set up three tomato seedlings in three plants. Feed plant A 0cups fertilizer, plant B 1 cup fertilizer, Plant B 2 cup fertilizer. Count number of tomatoes produced by each plant in 5 month period.

Independent variable here is: Amount of Fertilizer, that is the variable you are testing the effect of. You are actively manipulating the amount of fertilizer in your experiment.