This lesson is the 23rd lesson for the PA Common Core designed to address M08.C-G.3.1.1 (8.G.C.9) . Students should be able to derive the formulas for 3D solids from Area formulas of the base shapes. I teach this by making a table that starts with a Rectangle, Circle, and Triangle (and their area formulas). I add a 3rd dimension and the kids discover that the formula for volume is simply the area formula times the height. I usually use a deck of cards to show "stacked area". Lastly, I use a cone and cylinder of the same height to model how three cones fit into a cylinder. Then, we derive the volume formulas for pyramids and triangular pyramids.