When we decorate Easter eggs, I poke holes in the ends of the egg and drain it out and then rinse the shell out. This is the way I did it as a child so this is how I do it with my girls. It allows the decorated shells to stick around a bit longer and makes for a decorative center piece.
This year I remembered a fun science experiment you can do with the shells – make a salt crystal geode! All you need is egg shells, salt, boiling water and a small cup or bowl. Food dye is optional but it makes for a pretty geode. Full instructions can be found on Science Notes.
I have a collection of plastic cups that I save for kitchen science experiments, and these were the perfect size for keeping the eggs upright. I filled the eggs with boiling water and the dissolved salt, and we set them aside. In out kitchen, it took just over a week and a half to evaporate and leave behind some fantastic crystals.
A simple science experiment, basic ingredients and a cool outcome! The girls loved checking in on the crystal growth throughout the experiment, and they were quite please with the results.