I have this really vivid memory from my childhood: At vacation Bible school someone handed me a ball of white dough and told me to knead it. I did as I was told and soon discovered this dark spot in the dough. As I stretched and scrunched the dough, that spot turned into veins of bright green. I was amazed as it turned into a green marbled design. It took a long time, but I obeyed the adults and worked the color in until I had familiar green playdough.
On Friday in after care the children made play dough the same way. It was hard for them to get the color dispersed, but they loved doing it. It's funny that once the play dough was made, they were ready to play with something else, not play with play dough. I bet I had the same reaction after I got my green play dough finished.
Here's the recipe we used:
3 cups flour
1/3 cup salt
2 Tblsp. vegetable oil
1 cup water
We put only two drops of food coloring in each ball of dough, but the colors were more pastel than the dough pictured. Red turned out as more of a Pepto Pink. To make play dough colors dark, I recommend mixing the food coloring in with the water in the dough recipe because if you put many drops of food coloring into the ball of dough it will get everywhere when they knead it.