Fossilize Your Footprints

What You Do:

1. Recruit your child to help you fill the tray with playdough. Leave a couple of inches at the top so you can fill the tray the rest of the way with plaster later.
2. Encourage your child to press his hand into the dough to make an imprint. You can join him if you'd like! Talk about the consistency of the dough. Is it hard or soft? Does he think that this imprint would still be around many years from now if he left it here? What about an imprint in mud or sand?
3. Now, make imprints of other things! These can be leaves, flowers, shells, toys. Recruit the family dog or cat to make a few footprints as well! This works best with items that your child will still recognize when he sees the imprint.
4. If you'd like, you can start making plaster (see instructions below) while your child is making imprints.

Your child can do as much or as little of this as he'd like. When he is satisfied with his imprint, it's time to preserve them in plaster. Follow the steps below to complete your homemade fossil.

Preserving the Imprints With Plaster

What You Need:

• Playdough imprints in tray
• Plastic milk jug or juice carton
• Scissors
• 2 cups plaster of Paris
• Water
• Rubber glove or large spoon
• Small plastic toy animal

What You Do:

1. Cut the top off of the milk jug or juice container. Now you have a nice disposable container that you can mix the plaster in and throw away when you're done.
2. Put about 2 cups of plaster of Paris powder in the container. The plaster of Paris directions usually suggest one part water to two parts plaster (so 1 cup of water in this case), but start off with less water than you think you need.
3. Use your hand (with a rubber glove) or a large spoon to mix and smash big lumps.
4. Add more water, a little at a time, until a smooth paste is formed.
5. When it is ready to be poured over the playdough, the plaster will be the consistency of pancake batter or a milkshake.
6. Before pouring the plaster, use toy animals to act out a story about how fossils are sometimes formed:

   Once upon a time, a long time ago, a turtle (or other animal) walked through the mud at the edge of a river. Sometimes footprints in the sand or mud get covered up by more sand or more mud. Suddenly a flood of water came down the river pushing lots of sand with it. The footprints made in the mud got covered up and, over a long time, became a rock. Because they turned into a rock, they lasted a long time and we can still see them. These are called fossils. Fossils are remains of plants or animals that lived a long time ago that have turned to rock.

7. While the children are watching, pour the plaster on top of the imprints in playdough. You can even incorporate this into your story!
8. Even though the plaster will harden within 30 minutes, let it sit for 24 hours before peeling the playdough from the hardened plaster. Otherwise, the playdough will stick to the plaster.
9. Wash tools and hands with water. Note: Do not pour any remaining plaster down the sink. Throw it into the trash.

The fun's not over! When you do finally remove the plaster from the playdough, try asking your child to identify the imprints or tell a story about how these things became fossilized. You can even bury his fossil in the yard or at the beach for him to dig up, just like a real paleontologist!