I have done a color mixing lesson with edible clay using a recipe that was
in the old Art in Action series of artbooks. You use margarine, Karo syrup,
powdered sugar and food coloring . It is the consistency and look of play
doh. I give the students a small marble size of each of the primary colors
and two graham crackers. They mix and make new colors and press the clay on
the crackers. I give them two so they can eat one at school and take the
other home in a small zip lock bag. I did it with first grade and still have
high school kids say, 'remember when we did the edible clay?"