Home made chalk

I know you can buy sidewalk chalk at the dollar store, but this is fun and gets your frustrations out.
You need:
7 egg shells (dry)
1teaspoon flour
1table spoon water
paper towl


Crush egg shells the finest you can. Add flour and water. Stir toghether, this should make a paste. Shape, roll up in paper towel. Dry for 2 days. It really works, we tried it!