Here’s a messy and hands-on way to make a full rainbow with your toddler!
I squirted shaving cream into each of the 6 compartments of a muffin tin, then set out food coloring in the three primary colors.
Veronika was my helper to squeeze the color into each portion of shaving cream. We could make red, yellow, and blue just by squirting into three of the shaving cream portions. The other three portions required mixing: red + yellow made orange (alas, a sort of muddy one), yellow + blue made a bright green, and blue + red turned into a vibrant purple.
I had to work quickly, because Veronika immediately wanted to turn this into sensory play!
Soon she was scooping up portions of the colored shaving cream on craft sticks, stirring them, and smearing them together. I had intended to scoop out a bit of each shaving cream color and make an actual arcing rainbow, but she was so content that I let her play the game her way.
Was she as interested in the fact that we’d mixed up ROYGBIV? Not especially; this really turned out to be sensory play. But we had fun with this very messy rainbow!
Update: Because she loved this game so much, we did a repeat… but with a twist. This time, I mixed up the colors ahead of time so Veronika wouldn’t immediately begin mixing and matching them. Then, I showed her how to paint the colors onto the window in rainbow order.
“A rainbow!” she said with delight, and began dabbing on the paint, too.
As a bonus, this will actually leave your windows squeaky clean, since shaving cream is basically just soap. Veronika loved helping wipe off the excess with paper towels and then using a spritz bottle and paper towels, long after the shaving cream rainbow was gone.