Question

How many variables are altered in a good experiment?

Answer 1

There's three kind of variables which are Independent, dependent, and controlled.

Step-by-step explanation:

Answer 2

An experiment usually has three kinds of variables: independent, dependent, and controlled. The independent variable is the one that is changed by the scientist. Why just one? Well, if you changed more than one variable it would be hard to figure out which change is causing what you observe.