How to make eggshell geodes

Eating a lot of eggs this Easter? Here's a brilliant way to upcycle the shells. Crystal growing is the most glittery science - plus it's easy for even little ones to try if they have a bit of patience.
There are lots of materials that you can grow crystals from - for example, salt and sugar (which are ideal if you are doing this activity with small children) as well as Epsom salts and alum. All of these things are already crystals, they just need your help to grow bigger.
Our science subscription box provides everything you need to play with science, allowing you to build up a lab collection and experiment repertoire month by month. Head over to www.letterboxlab.com to sign up and start playing with science today!