The poem reads "Magic Playdough, oh so white, I make this wish with all my might. If another color does appear. We're sure to have a GREAT school year." Basically, you make your own homemade flour playdough recipe (or head to Fun in First for the included recipe). Leave it white, but in each portion, add a drop or 2 of food coloring to the middle, but DON'T knead it. When the student pulls out their playdough and begins to play with it, they will see it change color.
...this is totally genius. And not just for kids! This is what happens when you microwave a bar of Ivory soap! Then you can tear it up, color it, and mold it into shapes! It's not wet and messy, either! This is awesome!