Teaching abstract concepts to computer science students is a demanding task. Typical presentations such as white board drawings and PowerPoints are helpful, but it is even more effective to provide visual aids that enable students to perform their own demonstrations. This adds a tactile component to the learning process that enhances the visual and audible portions of a lecture. To this end, we have constructed a number of hands-on experiments using bouncy balls and ice trays. The materials are inexpensive, easily obtained, and can be retained by students for their own study. We have found this to be an effective way to turn abstract concepts into concrete examples. We believe that this practice has lead to enhanced learning for concepts in counting and probability.