What's the independent and dependent variable in this sentence?

"If students eat breakfast then they will have better scores on a test"

An independent variable is the thing that you are changing to see what will be affected. In this case the independent variable is if a student has breakfast.

A dependent variable is the one that is being impacted by the thing you manipulated. The dependent variable is if the students have better scores.

The way I remember the difference is that the dependent depends on the independent.