How to keep a child busy for hours in the summer: DIY: Giant Ice Cube Awesomeness - filled with plastic animals, dinos, and such. And I'm sure you could put in food dye before its frozen to color it like the ice block in the photo.
Painting with Watercolors, Glue and Salt - simple and fun. The glue creates designs on top of the paint. The salt creates a pretty starburst effect by soaking up paint pigments as the painting dries. And as an extra bonus: the salt sparkl