Take a 2 liter soda bottle, poke holes in it. Attach to a garden hose. Toss over a tree branch and let hang for a kids water sprinkler. I might actually make this! You can loop it over a tree branch and let kids bat it around for more watery fun!
A bar of Ivory soap .this is totally genius. And not just for kids! This is what happens when you microwave a bar of Ivory soap! Then you can tear it up, color it, and mold it into shapes! It's not wet and messy, either! This is awesome!