Light travels in a straight line through empty space, but when it bumps into an object, it changes direction. Some shiny surfaces, like the plastic report cover or a mirror, send or reflect light back to you. (Think of a ball bouncing off a wall.) The sides of the plastic tube inside the kaleidoscope reflect the beads, sequins, and confetti. The reflections bounce back and forth from side to side creating multiple images. When you turn the kaleidoscope, the pieces move, and you see a different design.