Make Your Very Own Rainbow

(Physics for ages 5+)


Have you been lucky enough to spot a rainbow in your life? Usually they come out on rainy days while the sun is shining bright, but maybe you’ve seen one while running through the sprinkler on a hot summer day. But how do rainbows happen? The video above shows how you can create your very own homemade rainbow. Here’s what you’ll need:



White sheet of paper
Clear glass or plastic cup
Sunny day (or a flashlight)
Adult supervision (Adult supervision at all times please)



  1. Fill your clear cup about half-full with water.
  2. Find a sunny spot in your home, usually near a window or door.
  3. Place the white sheet of paper flat on a table or the floor. Make sure it is in the sunlight.
  4. Now, set your cup of water on the sheet of paper so that the sunlight hits it. Do you see the rainbow yet? If the sun is shining bright, you can usually see a small rainbow reflected on the paper.
  5. If you cannot see the rainbow, try moving the cup. Lift it a few inches off the paper or move it closer to the window.
  6. If you are still having trouble spotting a rainbow, try using a flashlight or another source of light. Set your cup in the middle of the paper and shine the light on one side of it. The rainbow should appear on the paper on the opposite side of the cup.



Sunlight may not seem very colorful, but it is actually made up of many colors even if we can’t see them all the time. When sunlight hits the water in the glass, the light rays are bent and separated based on their wavelengths.

This bending is called refraction and it happens anytime light passes through water. When we see rainbows outside, they happen because of water in the air that is refracting the light and creating a large, colorful spectacle.