Science bob provides great visuals in the video and the demonstration set up. The materials are easy to obtain and can be substituted if items certain items aren't available or if you're trying to avoid a mess. Instead of an egg, an egg sized ball of play-doh can be substituted and for a paper towel tube, cardstock can be rolled into a tube shape and taped at the end. Another alternative is to have a small bean bag doll sitting on top of a flat cardstock over the cup and trying to remove the cardstock so that the doll falls into the cup, if it helps you can tape a piece of string to the cardstock for easier operation. This site provides a basic introduction into inertia, but students can research more information on Newton's three laws of motions for a deeper understanding.