This egg shell mosaic used the leftovers from my Easter eggs. The slightly aged look about the colors was the result of putting the eggs in the oven to dry out the membrane. They got slightly burnt, as it were. It gave a nice golden color to the eggs, however.

This project is one entirely up to the child. It is art, not craft.

Materials:
2 dozen colored egg shells, crushed. You may want to keep each color separate.
Construction paper
Elmers Glue-all
Foam paint brushes or craft sticks for spreading glue
Glitter
Plastic grocery bags

Time: up to 30 minutes

Method:
1) Remove the membrane.You can sometimes pull the entire membrane out before the egg is crushed, but if the egg shell is thoroughly dry, it should break along with the shell and you can pull the pieces apart. Heating in the oven is another way to solve the problem of the membrane.
2) Crush egg shells if not already done. Make sure the pieces are separate, unless you want a very large, 3 dimensional mosaic.
3) Spread the glue in any fashion you desire, to create your mosaic. I chose a starfish, but you can create any kind of picture if your colors are separate.
4) Add glitter if desired.
5) Carry home in a plastic bag, in case some pieces want to fall off. Keep flat until dry.