We see things because light bounces off of things and comes to us. But what is light really? Light is a wave, and properties of the wave tell us about the color and brightness of the light. (Make waves using a jumprope.) Sometimes, the colors that we see are made up of lots of other colors. (Use diffraction gratings to see rainbow. Then, look at a hydrogen lamp to see that there are only lines of light, not a regular rainbow.) In addition to what we can see, there are many different colors we cannot see. Like x-rays, infrared (show the light from a TV remote using the cameras on cell phones), and radio. There is also “black light,” also called ultraviolet light. It can make things glow (show laundry detergent under black light).