This is a science experiment that displays what water does to the shoreline of the ocean. In class, explain how the beach is made. It is made by the erosion of rock formations that are moved on shore by the waves. You can put sand in a cup and make a "land formation" and show what the waves do to it as they splash up to the beach.
Teaching science can be engaging with this hands-on activity. This experiment helps students see that weathering and erosion can be slowed down but not stopped. Check out this science teaching idea for your elementary classroom!