Check out this video on how to make easy playdough at home without any cooking or cream of tartar involved.
All you need to do is mix four ingredients plus water;
4 cups of flour
11/2 cups salt
2 tbsp oil
1 cup water
It's a wonderful and cheap creative activity for your kids.
P.S. for the best recipe on making playdough the other way; involving cooking, - see this first video .