Stir dry ingredients in a mixing bowl. Place mixture in a skillet and turn the temperature to low heat. Slowly add the water and stir until mixture becomes stiff. Too much water will ruin the consistency, so only add a little at a time.
When the dough starts to pull away from the side of the pan, it is ready. Make sure all the dough is pulling away from the sides. If the center is still more liquid-y, keep stirring until the consistency is the same everywhere. Remove from heat.
When the dough is cool enough to knead, separate it into as many batches as you want. Then add different food colors to each batch, kneading until the color is thoroughly mixed in. Alternatively, If you only want one color, you can actually add the food coloring into the skillet with the water when it is cooking.
Store in a ziploc bag.
*You could substitute some of the water with scented extract, such as vanilla, but if there are kids in the class with other food allergies, you may want to keep it nut-free, too.