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Rainbow science experiments

Rainy days mean a lot of rainbow activities in our house! We hope your kids enjoy these fun and easy rainbow science experiments!

I had fun reading about rainbows with my son, so we decided to do a few Science experiments as well. The Walking rainbow experiment, M&M (also known as the skittle experiment) and Milk experiments were all a hit. However this one below was the favorite. Let me show you how to do them.

Walking rainbow experiment

This walking rainbow science experiment is such a fun and easy activity that all kids will love! Your kids will be amazed as the colored water travels along the paper towels and into the empty cups, making a rainbow. It’s magic!

This the perfect activity to introduce color mixing to your kids. Have them make predictions about what is going to happen and what colors are going to fill the empty cups.


  • 6 clear cups or jars
  • Water
  • Red, yellow and blue food coloring
  • 6 paper towels

Here’s how the magic works:

  1. Gather 6 clear cups. Fill 3 of the cups 3/4 of the way full with water. Add 5 drops of red, yellow and blue food coloring to each cup of water.
  2. Place the cups in a circle with an empty cup in between each colored cup. Fold a paper towel in half two times horizontally to create a long strip and place between each cup to connect all of the cups.
  3. Watch closely and wait for colors to travel through the paper towels and into the empty cups and a rainbow to appear. The water travels pretty quickly through the paper towels, but it will take a couple hours for the empty cups to completely fill with water. Leaving the cups overnight will make a very vibrant rainbow to wake up to in the morning.

*With older kids, you can talk about why the water goes up the paper towel and fills the empty glass. This action is called Capillary Action, which is basically liquid that moves through a different material against gravity. Some other examples of this happening are when water moves up a straw or when water moves from flower roots all the way through the stem to the petals.

m&m rainbow experiment

M&M experiment

This M&M science activity is mesmerizing for the whole family! Little kids and big kids alike will enjoy seeing the “magic” happen with just 2 simple ingredients.


  • M&M’s or Skittles
  • Water
  • Glass plate

It’s really simple! All you do is:

  1. Place M&M’s in a circle around the outside of a plate, alternating colors.
  2. Slowly fill the center of the plate with water until the water is barely touching all the M&Ms.
  3. Wait and watch for a rainbow to appear in the center of the plate.

Older children might enjoy trying to make different shapes or patterns with the M&M’s. Hearts are always a big hit. It would also be fun to try with different holiday M&M’s.

Fizzy color mixing

This fizzy color mixing activity is a fun way to teach your kids about mixing colors.

Talk with your kids about the primary colors and how they are the 3 colors that make every other color. Make predictions of what will happen when you mix baking soda and vinegar. What will happen if they mix certain colors.


  • Food coloring
  • Water (you can use the leftover walking rainbow jars)
  • Vinegar
  • Clear cups or jars
  • Ice cube tray
  • Baking soda
  • Large container or bin
  • Medicine syringes

Here’s how you do it:

  1. Fill 3 clear cups with half water and half vinegar. Add 5 drops of red, yellow and blue food coloring to each cup. (Or use leftover cups from Rainbow science experiment and add 3 Tb of vinegar to each cup)
  2. Put ice cube tray and cups in a large container. Add 1 drop of red, yellow and blue food coloring in random ice cube slots and cover each slot with a spoonful of baking soda.
  3. Give your child medicine syringes and let them mix the colored vinegar water into the ice cube trays. Watch to see what color appears and watch it bubble in the ice cube tray.

milk experiment in glass bowl

Rainbow milk experiment

The milk magic is a fun Science experiment to watch. While it doesn’t last long, the kids like watching as the detergent interacts with the fat molecules in the milk.


  • Pie dish
  • Q tips
  • Food coloring
  • Liquid Dish soap
  • Whole milk

Here’s how you do it:

  1. Fill milk about half way in a shallow pie dish.
  2. Place food coloring dots around the top of the milk.
  3. Dip a Q tip into the dish soap and then into the food coloring.
  4. Watch the colors explode!

Hope you enjoyed these kids Science experiments! Don’t miss the free printable rainbow coloring page to go along with these activities!

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