Answer:
Independent: Purposely altered
Dependent: Changes with respect to the independent being altered
Controlled: Never changes
Step-by-step explanation:
An independent variable is a variable in which does not rely on other pieces/variables of an experiment to assume a value. In other words, it does not change when other variables change. However, it can be changed intentionally by the scientist.
A dependent variable is a variable in which its change in value relies on other pieces/variables of an experiment to assume a value. So, if the indeoendent variable is changed, the dependent variable will change as well. The opposite is not true though - if the dependent variable changes (for whatever reason), the independent variable hasn't necessarily been changed.
A controlled variable is a variable that stays CONSTANT throughout an experiment. It is never changed, and nothing will change it. An example of a control variable is the number of participants in a study: no more participants are being added, and no participants are being removed. The number of participants remains STATIC throughout the study.