Summary

Learn more about how fossils are formed, and then create your own fossils using art supplies.

Materials

• Photographs of real fossils, from books or from the Internet
• Large piece of recycled cardboard, plastic tarp (or other disposable work surface)
• Modeling clay or play dough (homemade or store-bought)
• Waxed paper
• Small objects to turn into "fossils": seashells, fresh leaves, small plastic dinosaurs
• Vegetable oil and brush (or non-stick cooking spray)
• Plaster of Paris
• Plastic mixing container that can be thrown out
• Water
• Plastic spoon

Related Video Clip

Dinosaur Train: Fossil Fred and a.k.a. Bones (2 minutes 5 seconds)

Procedures

1. Ask students if they know how long ago dinosaurs like Tyrannosaurus rex and Triceratops lived. After considering some answers, explain that these animals lived a long, LONG time ago – millions of years ago - before there were any people around. Many students will be surprised that no person – not even cavemen ever saw a dinosaur. So, how do we know these large animals once lived on our planet? Answer: When these animals died, they left behind clues known as fossils. Many students will have heard the word fossil, and some might have some idea of what they look like, but most probably need further explanations about how fossils are formed.
2. Show a photograph of a fossil. Explain that fossils are stones that look like plants or animals that lived long ago. When most living things die in the wild, some other animals survive by eating the dead animal's remains. (Use age-appropriate explanation.) But sometimes, rarely, when a plant or animal dies, and gets covered with mud, sand or soil. Over long periods of time (millions of years), the animal's bones turn into stone.
3. Show students a video clip from "Fossil Fred." Afterward, ask them to discuss how fossils are made..
4. Tell the students that even though real fossils usually take millions of years to form — they are going to make models of homemade fossils in just one day.
5. Working on a large disposable work surface (cardboard or plastic), have students press and roll around a large ball of clay or play dough on a large piece of waxed paper. The goal is to make the ball as smooth as possible.
6. Press some small objects (bones, shells etc.) deep into the surface of the clay or play dough. Then remove them to see their impressions.
7. If working with play dough instead of clay, let it dry overnight. If working with clay, continue to the next step.
8. Brush a small amount of vegetable oil into each impression (or apply small amount of cooking spray).
9. Prepare a batch of plaster of Paris according to the package directions. The goal is to make it smooth but thick. Help students spoon the plaster into each impression until it is filled.
10. Wait about 30-60 minutes for the plaster to dry completely. Then peel away the clay or play dough to reveal the fossil.
11. IMPORTANT: For clean up, throw out the container used to mix the plaster. Do NOT rinse this container in the sink, as it can cause plaster to set in the pipes.

Extensions

1. To give students the experience of excavating (digging out and removing) fossils from stone, they can first "bury" some bones and shells in a batch of plaster of Paris, that is then allowed to harden inside a disposable container such as an old milk carton. Students then can use simple (non-sharp) tools to scrap the plaster away until the hidden objects are revealed.
2. Older students can use chicken bones to create complete skeletons. Use photographs of real fossil skeletons as a model.