Preschoolers can create and decorate two- or three-dimensional dinosaur eggs. Cut large egg shapes from construction paper, brown paper bags or poster board. Let the preschoolers draw or paint the eggs. Then cut out a white "inside" for the egg, and have the preschoolers color in baby dinosaurs. Attach the "inside" to the back of the egg, or hang it next to the egg. For three-dimensional eggs, have the children create egg shapes from modeling clay, or give them large Styrofoam egg shapes to decorate. Let them use their imagination to come up with what they think dinosaur eggs might have looked like.
Children love playing in the sand, and creating fossils for little archaeologists to hunt can be a lot of fun. Collect some small plastic dinosaur models. Fill a small cup halfway up with sand, and stick a dinosaur model on top. Pour plaster of Paris over it and let it set. Remove the plaster mold from the dinosaur and stick it in a bigger pile of sand, such as a sandbox. Let the students "dig" for their fossils with tiny brushes or toothbrushes. You can also make salt dough with your preschoolers and let them press dinosaurs or their own hands and feet into it to make "fossils." The fossils can be painted as well.
Let your preschoolers make dinosaur puppets and put on a show. Puppets can be made from socks, paper bags or dinosaur pictures glued to popsicle sticks. Collect some fake plants such as plastic ferns, and set out a landscape with green and blue drawings or construction paper for land and water, turning part of the classroom into a little dinosaur environment. Give the preschoolers crafts to decorate their dinosaurs, and discuss the history of the dinosaurs, such as what they ate, where they lived and what may have caused their extinction. Let them pretend to be the dinosaurs, or have them put on a short play for their parents.
Show the preschoolers pictures of artists' renditions of dinosaurs, and ask them to make their own in paintings or with modeling clay. Have them stick the palm of their hand in paint and make a hand print on a sheet of paper, then have them turn it into a dinosaur, such as a stegosaurus. Lay out a giant roll of paper and let the preschoolers color a dinosaur habitat all over it. Create a dinosaur diorama with clay models that the students make, letting them describe the environment and the types of dinosaurs in it. You could also bring in recycled materials, such as milk cartons, and let the preschoolers turn them into dinosaurs with paint and supervised use of glue and scissors.