Here's what you can do with a prism!
|| You can make a rainbow
|You can shine a red laser through it|
|You can shine a red and green laser through it|
A prism works because the different colors of light travel at different speeds inside the glass. Because the colors of light travel at different speeds, they get bent by different amounts and come out all spread out instead of mixed up. Violet travels the slowest so it is on the bottom (least bent) and red travels the fastest so is on the top (most bent). The other colors are somewhere in between. When the air is full of water, like after a rainstorm, the water droplets act like a prism and can make a rainbow. Rainbows are circular in shape because the prisms (raindrops) that created them are spherical.