I got this recipe a long time ago, and then lost it. I was just going through some things and found it! This is a great recipe, and I think it turns out better than the stuff that you buy.
2 Cups Flour
1 Cup Salt
2 1/2 Teaspoons Cream of Tartar
1 Tablespoon vegetable oil
2 Cups water
Over medium heat, cook until it is play dough consistency, aproximately 5 minutes.
Divide in to parts and add food coloring. Knead coloring in to dough. (should use gloves). If you don't want separate colors of dough, you can just add the coloring in while you are cooking it.
For older children, add a package of koolaid to give it a good smell, and glitter to make it fun.