Learning About Primary Colors & Rainbows With Ice Cubes

by Destri on March 14, 2012

Primary Colors activity

This time of year you see rainbows everywhere.  Spring and St. Patrick’s Day crafts put the elusive wonder of the sky front and center.  So I came up with a simple and interactive way to show my kids how the colors of the rainbow are made.  More specifically, how they can be made with primary colors.  My kids are too young to get into how rainbows are made without going glassy eyed, so we just started with learning the colors.  This is a great activity for toddlers, preschoolers, and on up.  If you’ve got some bored kiddos and want a mother-of-the-day award – grab an ice tray and catch me after the jump!

Primary Colors Ice Cube Activity


  • red, yellow, and blue food coloring
  • ice cube tray
  • 6 or more clear cups filled with water
  • something to stir with

Setting It All Up:

Fill the ice cube tray with water about half full if you are using a standard ice tray.  I had a little one, so I filled it all the way up.  With the food coloring, add 1 drop of one color to each cup.  I had quite a few of each so they could experiment.  Put in the freezer at least an hour before the activity.

Set all the cups with the water out, and have them gather around.

Add the red, yellow, and blue food coloring to the cups, one per cup.  While I did this I asked them if they knew what the colors of the rainbow were and talked about each. Then I asked them if they thought we could make all the colors of the rainbow with only the three primary colors we had.  They said no…oh boy were they in for a treat :)

I took out the ice cubes and let them know that they were the same 3 colors that were in the cups – primary colors.

Then I asked…”What do you think would happen if we put a red ice cube into a yellow cup?”

My 3 year old dropped it in, then stirred. “Orange!” They scream.  I didn’t expect them to get so excited, they were jumping up and down and the whole bit.

“Well if red made yellow turn orange, what do you think would happen if we added blue to yellow?” Was the next question.  My 5 year old did this one…”Green!”  They were even more impressed with this one.

Next up was red and blue, which made the purple. We tried to get an indigo, but couldn’t quite pull it off.

Then I had them do the opposite, by adding the yellow ice cubes to red and so forth to help it sink in.

Of course, we had to see what would happen when we mixed all the colors and made brown.

Then I lined up the colors in order and said “See, we made all the colors of the rainbow!”  They thought it was pretty cool.

There was one red ice cube left and I saw my little girl eying it, thinking she was going to ask if she could add it to a cup.

“Can I eat it?” she asks.  She’s a girl after my own heart :)

Making rainbows with milk is another fun activity with the kiddos, and super simple too.  You’re going to have all sorts of awards ;).

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