A fun recipe for making sidewalk chalk... out of eggshells! Great after you had made a lot of devilled eggs or egg salad sandwiches.

Eggshells from 12 eggs
2 tsp flour
2 tsp hot water
Powdered tempera paint (optional; in colors for chalk)

Wash eggshells carefull, removing film (membranes) on the inside. Dry. Place eggs in ziploc bag (freezer bags work best since they are thicker) and crush eggs with a rolling pin or other similarly shaped object until eggshells are crushed into a fine powder.

Pour eggshells into a bowl. Add flour and optional paint, stirring well. Add hot water, mixing until a thick paste/dough forms. Roll into tube shapes for chalk. Allow to dry (about a day). Use!