Since I have a child at home, we often try out different activities for library programs at home to see how they work. Our theme this year is "Dig Into Reading" and one of my colleagues found this fun activity for Magic Treasure Rocks at Growing a Jeweled Rose. It's super fun and simple and incorporates science!
The rocks are made from water and baking soda and require around 24 hours of dry time. You can put little treasures inside that are revealed as the child sprays vinegar on them.
Here's a little video of how they work!