Materials
Masks9 cups of fiber-reinforced ready-mixed concrete2 cups (480 ml) water
Small tub or bucket
Stick or large, old spoon
Wax paper
Scissors12" (30 cm) round, plastic plant drain tray with straight vertical sides
Latex gloves
Objects to press into concrete (see below)Paper towels, if necessary
Damp cloth
Instructions
1. Help the children (and yourself) put on masks because of the concrete dust.
2. Using a stick or old spoon, mix the concrete with 1 3/4 (420 ml) cups of water in a tub or bucket. Add all the water at once and stir well to moisten all of the dry powder. If more water is needed, add one teaspoon (5 ml) at a time until the mixture has the consistency of thick brownie batter. (Less wet is better.) Note: The concrete is easier to use if you measure it out and place it in freezerbags prior to involving the children.
3. Cut out a 12" (30 cm) circle from wax paper. Place it into the bottom of the plant drain tray (this will be the mold).
4. Pour the mixture into the mold. Use your hands, a spoon, putty knife, or stick to press the mixture down into the mold. (If you use your hands, put on latex gloves.) Jiggle the mold from side to side to level the surface.
5. Clean the tools immediately with water spray from a garden hose worksgreat. DO NOT RINSE THE RESIDUE DOWN THE SINK.
6. Help the children make a handprint or footprint in the concrete. For added interest, add stones, marbles, or tiles. Or make shapes using cookie cutters or draw letters with the point of a rattail comb or stick. Some suggestions for adding items are:* Push in objects half way so they will stay in place and will not fall out.* As soon as your craft stick makes a dry, clean mark, you are ready to begin.* Push the writing tool into the mixture do not drag it.
7. If the stone seems very wet, soak up some of the water by placing a papertowel on the top of the concrete. Depending on the dampness of the mixture,you will have ten to forty minutes to complete the stone.
8. Put the stone in a place where it does not have to be removed for twenty-four hours. If you move it before it dries, some of the letters, shapes, and prints may disappear. It could also crack.
9. Once the stone is firm, cover it with a damp cloth for a few days to make it stronger. Wait at least two days before trying to remove the mold. Then, wait at least two weeks for it to cure before putting any pressure on the stone or putting it outside.Note: A sixty-pound bag of concrete makes seven to eight stones.More to doThis activity is great when the children are learning about dinosaurs or fossils. The children are making their own fossil prints. It provides an example of how dust and dirt-like material can become a solid, like the fossils.
