Have you ever dyed Easter eggs and thought that a slightly-different-colored egg wasn't worth the trouble? How about an egg filled with crystals? Try out a chemistry experiment that lets you turn eggs into geodes.
Geodes, as anyone who has ever wandered through an 'educational' toy store knows, are minerals that have air pockets in which multicolored crystals grow. Generally they're sold as lumps of rock which are cracked open by kids and will help them learn . . . something. Possibly how to use a hammer.
You might teach them a little more by showing them how to make their own "geode" with an egg, water, and a few chemicals. Eggs, with their shells of calcium carbonate, form pockets in which crystals can grow, if the appropriate solution is added to them. How amazing the effect will be depends on your skill with eggs. Cracking an egg carefully in half can let you fill both halves. Taking a little sliver of egg off the top will create a more impressive geode that can be cracked open. And then there's the gold standard of egg decoration, making a tiny hole in the top and bottom of the egg with a needle, puncturing and mixing the yolk, and blowing the contents of the egg out one of the holes.
However you open the egg, make sure it's clean inside before you proceed. You'll need a quarter cup of hot water, and some chemicals. One of the most common chemicals to use to make an egg geode is copper sulfate. You can find it in hardware or home improvement stores. It's used to keep algae out of pools and septic tanks. Dissolve the crystals in water, adding a little at a time until no more will dissolve. Remember, the hotter the water, the more crystals will dissolve and the better results you'll get. Pour the water into the egg shell, and leave it to dry. A layer of blue crystal should form over the next few days, after which you can pour out the extra liquid. If you leave it for a week or so, the entire thing will crystalize. After it crystalizes, it will need to be stored in a dry, sealed container. Or you could simply dissolve the copper sulfate in water again - after admiring your egg properly - and clean your septic tank.
If you don't want to work with copper sulfate, you can use epsom salts the exact same way. I suggest making clear crystals first, but you can also add some food dye to the solution and make green, red, or yellow crystals. People can make egg geodes with borax, with magnesium sulfate, and even with table salt. (That might be the ultimate way to serve the salt at your next hipster dinner.)
Then go back to the educational store and go ahead and buy a geode there. It's fun to use a hammer.
Top Image: Thinkoholic