Would You Eat a Blue Potato? (1988)

Katie and Scott are invited to eat at the home of Figment the dragon. The snack consists of green milk, blue potatoes, pink cauliflower, and orange sandwiches. Figment realizes the food just doesn't feel right to the children. They read a story of a sad king who painted his kingdom blue to match his mood. The children go through a series of "colorful" experiences and discover color through their senses and imaginations—imagining how the world would look and feel if everything was just one color. In the end, the children realize they like all the colors together best of all—and the King agrees!