Factor being changed in a controlled experiment is called the?

The factor changed is the independant varible, the thing that the scientist can change each time they run the experiment. The control is the part of the experiment that the scientist determines stays the same.

Ex. They have one person eat a Milk Chocolate and a dark chocolate and then ask which one they like.

The person is the control because it stays the same.

The chocolate is the independant varible because the type changes.