I have to do a project for my AP Calculus AB class using an object and the concept of solids of revolution. I figured out the volume by getting data points, graphing it on excel, finding the formula of the regression curve, and then integrating it. But we are also required to find the volume using a different method. The method suggested is filling the object with water and then measuring the water used. It also says you can use a Riemann sum. The only way I remember using Riemann sums was to find the area underneath the curve. So how are you supposed to find out the volume this way?