Hand Boilers, perfect for teaching about thermal energy, are sold individually and in cases of 12 for your entire class. Place the Disk and Ring Kit in a dishpan of hot water and watch it expand. Does the hole in the center get larger or smaller? Click a metal disk in the Chemical Heat Pack and watch the liquid crystallize. Thermoplastic Polymer can be heated and molded over and over again. The Soft Shell Ice Cream Ball is a great way to teach how adding salt to ice lowers the temperature of the resulting solution.