What's the control and constant for my science fair project? My project is '; sand under lateral compressions.';?

its about platesWhat's the control and constant for my science fair project? My project is '; sand under lateral compressions.';?
ok well we use differnet terms at my school, the control and variables we use, but the constant is what stays the same in the experiment, ie, the thing you dont change and make sure is always the same, the control is the thing you purposely change to get different results