First, buy plastic dinosaurs from a dollar store. They should be 2- to 3-inches in length. The hard plastic dinosaurs work the best. You will also need Plaster of Paris, sand, a disposable plastic container (like a large cottage cheese container) and Styrofoam cups.
Then, you will need to mix the Plaster of Paris with water. Add sand until you have a thick, grainy mixture that still pours. Pour the mixture into a Styrofoam cup until it is half full. Wiggle a dinosaur into the mixture, making it sure it doesn't reach the bottom. Finish filling the cup. Make one cup for each student. Allow them to sit for two days.
Peel the cup off of the mixture. Give the children plastic knives or use sticks. Let each child excavate his own dig. The fun grows once the first child finds his or her dinosaur. Now that they know they each have one, the others dig with more intensity to discover which dinosaur they will discover.
The expression on his face expresses how much fun he had. This is a fun way to introduce or conclude a unit on dinosaurs.