What is the difference between a constant and control variable?

thanks i can't find this anywhere or in my book.What is the difference between a constant and control variable?
a constant is number like 2 or pi or 3/4. It is not a variable at all.





A control variable is the independent variable in a relationship, especially one that humans can manipulate while collecting data. For example, if you had a pot of water on a stove, and you wanted to graph the relationship between burner temperature and the time it takes the water to boil, then burner temperature is the control variable, as you are controlling it with the burner setting knob.What is the difference between a constant and control variable?
they're the same thing.