what should you ask yourself when looking for an independent variable in an experiment?
I would ask whether that variable can be manipulated or not.
Here is more info on experimental variables that might be helpful.
An independent variable is the potential stimulus or cause, usually directly manipulated by the experimenter, so it could also be called a manipulative variable.
A dependent variable is the response or measure of results.
Extraneous variables — other than the independent variable — potentially can affect the dependent variable, so they must be controlled. If possible, you try to keep them constant between the experimental and control group.
The experimental group receives the independent variable.
The control group is similar to experimental, except it does not receive the independent variable. Extraneous variables are balanced between experimental and control groups.
I hope this helps a little more. Thanks for asking.