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!
DRAMATIC PLAY AREA - Sue has gotten us a lot of wonderful, new, indoor gym equipment, but at this time of the year, I can't help but "Think Spring". Wouldn't it be fun to build something like this to put in the grass at the far side of the playground?