1/2 cup cornstarch
3 T sugar
2 cups cold water
squirt of dish washing liquid
Mix together cornstarch and water. Stir in cold water and dish washing liquid. Whisk together. Cook until thick (will thicken more as it cools). Divid into four containers. Add food coloring or tempera paints to color.
This can be cooked on the stove or in the microwave. If you choose to microwave, take out every 30 seconds to whisk for a total of about 2 1/2 minutes.