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How to Make a Rainbow

 Posted by on February 28, 2013
Feb 282013

Learn how to make a rainbow like the ones you see in the sky using materials you probably have on hand.

How to Make a Rainbow

How to Make a Rainbow

Here’s what you need:

How to Make a Rainbow

  • clear glass of water
  • a piece of white paper
  • masking tape
  • flashlight
  • (possibly will need a can or jar)

How to Make a Rainbow

  1. Cover the flashlight with two pieces of tape leaving a slit in the middle.
  2. Shine the flashlight through the glass of water onto the piece of paper.
  3. The rainbow should appear on the paper.  {Turn off the light to see it better.}
  4. You may need to sit the glass on top of a can or jar of peanut butter {in my case} to raise the glass up higher.
  5. Play with the angle of light shining through the glass until you get a good rainbow.  For me, shining the light near the top of the glass {by the rim} worked the best.
How to Make a Rainbow

Light shone through one angle.

How to Make a Rainbow

Light shone through another angle.

Want another cool and easy way to make a rainbow?
Grab a CD or DVD and a flashlight.  Shine the light onto the DVD.  A rainbow will appear.  {You may not even need the flashlight.  Overhead light may be enough to see the rainbow.}
How to Make a Rainbow

The Science Behind It

The light from the flashlight (white light) contains all the different colors of light (Red, Orange, Yellow, Green, Blue, Purple {or Indigo and Violet if you prefer}).  When you shine the light through the water or onto the DVD, it refracts (bends) and splits into the different colors.  This is because the different colors (wavelengths) of light behave slightly differently as they travel through the water and glass.

More Rainbow and Play Ideas

Then, for even more rainbow awesomeness, check out all of the rainbow posts below.

This post was originally published on April 25, 2012. The Outlaw Mom organized a blog hop to bring you our favorite ideas for kids involving rainbows.


Enjoy the rainbows!



Linking up here.

  11 Responses to “How to Make a Rainbow”

  1. Hey that is a great idea – my children will love that.
    I don’t have a rainbow activity we have done but shall link you up on my memes page.

  2. Wonderful activity. We just watched a Magic School Bus episode about making rainbows from white light. We’ll be trying this very soon!

  3. Love this! Going to try it today!

  4. OOh this is fab. Was thinking about the prisms we used to have in school science to make rainbows and have been thinking how do you create rainbows without the special prisms – now I know all I need is a torch and a jam jar – can’t wait to try this with my 4 year old. Thanks for sharing. Ellie

    • I’d love to hear how it went for you! You may need to try a few different kinds of glass. I tried with a Mason (canning) jar and couldn’t get it to work, but a regular juice glass worked just fine.

  5. What a cool experiment! Love all the rainbow posts in the linky, too!

  6. Lovely, thank you for sharing!

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