Sidewalk Chalk Paint

You need:

-liquid food coloring (like what you find in the spice section at the grocery)
-box o' corn starch
-water
-minimum 8 oz individual containers for each color


Method:
-Measure 1/4 cup cornstarch into each cup.
-Add 1/4 cup water to each.
-Drip in 5-10 drops of food coloring.
-Stir it up. At first it will seem as though the cornstarch just won't mix in, but all at once it comes together. Just don't put the water in first or it's significantly tougher to get it to mix up.

(librarycollective.blogspot.com)