Great list for Outdoor Summer Fun. Some new and amazing ideas I haven't seen yet to keep kids busy this summer. Worth a look for the links alone! 30 out of the box ideas (and awesome links to support you in doing them.
Elephant Toothpaste - cup hydrogen peroxide liquid is a solution, which can be found at a beauty supply store or hair salon), 1 Tbs (one packet) of dry yeast, 3 Tbs of warm water, liquid dish washing soap and food coloring
Sidewalk Chalk Spray-All you need is Flour, Food coloring, and Warm Water. A tablespoon of flour, 10 drops of food coloring, and about a half cup of warm water. Shake it up in the bottle and let your kid go nuts.