After a rainstorm, the sun comes out and Sid spots a big rainbow in the sky. He races inside to tell his parents, but by the time he brings them outside to see it, the rainbow is gone. Sid and his friends investigate rainbows at school where they discover that rainbows can only form when light passes through water droplets. Includes four episodes: Let There Be Light, Discovering Darkness, Shadow Smile, and A Rainbow Every Day! Stories Include: - Let there be Light - Discovering Darkness - Shadow Smile - A Rainbow Every Day!.