Homemade Eggshell Sidewalk Chalk

Crushed eggshells become real chalk you can draw with outside — a small science-into-art experiment.

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Ages 3-620 min plus 3 days drying prep

We save eggshells on the windowsill for a week before we do this, which my kids find hilarious and slightly disgusting.

Crushing them is the best part. Then it turns into a science lesson without anyone noticing: powder plus flour plus water, poured into molds, left to dry for two days.

Drawing on the driveway with chalk you made from your own breakfast is a very specific kind of satisfaction.

Crushed shells, flour and water becoming a thick paste

Dry sticks of homemade chalk and the first driveway drawings

The chalk drying in the mold next to the leftover paste

What you'll need

6-8 clean, dry eggshells
A mortar and pestle or a zip-top bag and a rolling pin
1 teaspoon of flour
1 teaspoon of very hot water (adult handles)
A drop of food coloring
Toilet paper tubes cut in half, lined with wax paper (the molds)
A small bowl and spoon

How to make it

1
Save eggshells from breakfast for a few days. Rinse them well and let them dry.
2
Together, crush the eggshells in the mortar until they become a fine white powder. This takes real muscle — take turns.
3
Measure out 1 tablespoon of eggshell powder into a bowl.
4
Add the flour and hot water. Stir into a thick, smooth paste.
5
Drip in one drop of food coloring and mix until the color is even.
6
Spoon the paste into the wax-paper-lined tube molds, packing it down with the back of the spoon.
7
Let the chalks dry on a windowsill for 3 full days until rock hard, then peel off the paper and take them outside to draw.

Tip

The chalk will feel damp on day one and chalky on day three. Patience is part of the magic.