The children learned how dinosaur fossils were made by making some of their own. Since dinosaurs no longer exist, we used plastic dinosaurs to fall into the soft soil (wet sand). The children then pushed the dinosaurs down and made an imprint. We added soft soil (plaster of Paris) to the tops of the imprints and let it harden like rocks did. The next day the children were able to use their paleontologist tools to clean up their new fossils.