Glow stick xylophone. Put the glow sticks in cups of water and an aura comes off in the dark, when you tap them. Probably the coolest thing ever.
How to make your bath water glow and other totally awesome things to do with your kids. (This website is amazing!!) Ill be happy I pinned this someday!
It's alive! One of the coolest science experiments ever!
Another pinner says: glow in the dark slime UPDATE: made this and it was every bit as cool as I had hoped. Not sticky (was afraid it'd be sticky on the hands) and therefore not messy. and it glows! :)
Water Piñatas! Great for a hot day with the kids for fun! Just think about these with a waterproof prize in each. FUN!!