Mixing Colors

There are three primary colors of light are red, green, and blue.  The three primary colors of paint are red, yellow, and blue (I know it’s actually cyan, yellow, and magenta, which we’ll get to in more detail later, but for now just stick with me and think of the primary colors of paint as red-yellow-blue and I promise it will all make sense in the end).

Most kids understand how yellow paint and blue paint make green paint, but are totally stumped when red light and green light mix to make yellow light. The difference is that we’re mixing light, not paint.

Lots of science textbooks still have this experiment listed under how to mix light: “Stir together one of red water and one glass of green water (dyed with food coloring) to get a glass of yellow water.” Hmmm… the result I get is a yucky greenish-brown color. What happened?

The reason  you can’t mix green and red water to get yellow is that you’re essentially still mixing paint, not light. But don’t take our word for it – test it out for yourself with this super-fast light experiment on mixing colors.


  • pair of scissors
  • crayons
  • sharp wood pencil or wood skewer
  • index cards
  • drill (optional)
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6 Responses to “Mixing Colors”
  1. Aurora says:

    Red and green LIGHT make yellow, just like in the video. What color did you get with orange and green?

  2. mirzamediha says:

    we tried orange and green, is that the right combination to get yellow?

  3. Maricelli Pena says:

    wow that’s so cool I saw Red pink and green that is the coolest Ivever seen in my life

  4. Aurora says:

    Yes that’s right! Which part did you have trouble with?

  5. Amy Breeden says:

    Is the answer to making yellow – red and green? We are guessing that is it from the flashlight project, but can’t get it to work with this project.

  6. Pamela Szczech says:

    i love this
    it is so cool i did not know that you can do that just by turning the surer


    Ellie Szczech

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