Summer break is coming. Which means it’s time to bring the classroom home, and keep young minds active for the next few months. Here are a quick scientific activity to spark curiosity and discussion in your own home. This will help remind your summer scientist that science rocks!

Eggshell Geodes

This is an easy activity with impressive results. It does need a little prep-work. The first step is to get your eggshells. Crack open as many eggs as you want to use as close to the narrow end as you can. You want as much of the shell intact as you can get, so they make a cup. Make sure you clean them thoroughly in hot water, so that the membrane is all out.

For the activity itself, you need your eggshells, a selection of soluble solids (various kinds of salt, sugar, baking soda, borax, cream of tartar, etc), food coloring, a cupcake tin, and a couple coffee mugs. And of course, hot water.

You (the responsible adult) begin by making a supersaturated solution with any of your solubles you want to use. Do this by pouring 2 parts boiling water over 1 part powder, stir to dissolve, then keep adding more of the solid until no more will dissolve. Then let your little helper choose the colors of food coloring.

Set your eggshells into the cupcake tin so they stay upright, and carefully pour the solution in, filling them as full as you can.

Set them somewhere safe, and wait! As the water evaporates, crystals will form inside the shells.

As you and your kid check on them (careful not to jostle the tin), observe the types of crystals. Do different solids make different crystal shapes? How fast is the water evaporating? Does that change with the local weather? When the geode-eggs are completely dry, they can last a long time with careful handling in a dry space.