Many people remember salt dough from third-grade geography lessons: slap a big blob down through the Western states, paint it with green and brown watercolors, and you just created the Rocky Mountains. It was also useful when forming the Hawaiian islands.
What most people don't know is that salt dough is an excellent material for three-year-olds making a nativity scene. Specifically, salt dough, toothpicks, and googly eyes. My Nursery class made these little nativity sets - our teacher made Mary and Joseph and we got to create the manger and any animals we saw fit. I believe mine is a cow.