One of the best instructional videos on volume. Please give it a watch and remember the equations especially those for the more difficult shapes like pyramid, cone and sphere. ,

Not everyone can just simply remember equations so this video shows a few other methods for remembering the equations of the different shapes (The accent is a little difficult to understand but the video is easy to understand)

This link will take you to the kahn academy page looking at solid objects and their volume . Just click here