Exploding Rainbows

exrainbows The children will create a rainbow in a new and very interesting way.


  • To introduce the concept of primary colors and secondary colors and encourage interest in science by observing cause and effect

Before You Start:

Explain to the children that there are three primary colors that all the other colors of the rainbow are derived from. Set up a station with the milk in the pan, the soap and colors in a ready container and the pipettes at hand. You will need: dish soap, eye droppers or pipettes, large pan (wide and shallow, Liquid Watercolor™ (red, yellow and blue) and whole milk at room temperature.

Let's Get Started!

Step 1.

Show the children a lasagna pan of warm whole milk and ask how many colors they see. Tell them to pretend the pan is like a sheet of white paper.

Step 2.

Show the children a glass of water. Drip a couple of droplets of dish soap in the water and watch them slowly sink.

Step 3.

Explain that even though the soap is a liquid just like the water, it is heavier than the water and therefore sinks.

Step 4.

Point out that the soap sinks slowly. Bring out an eyedropper of milk. Ask the children what they think will happen when the milk is dropped into the water. Write down their responses.

Step 5.

Dribble the milk and observe as the milk separates and makes the water opaque. Explain to the children that even though they can no longer see the soap droplets, they are still in the glass. The lasagna pan is the same way: When they dribble the soap, it's difficult to see the soap, but it's still there. There is another way we know the soap is still there - this is when I start the experiment and gesture for the child to pick up a pipette of one of the primary colors.

Step 6.

Now, allow the child to dribble a small amount of the red, yellow and blue into the milk.

Step 7.

The color will float on top until the soap is added.

Step 8.

Encourage the child to only drop a small amount of soap-one or two droplets.

Step 9.

Then encourage the child to explain what they are seeing. It is important that they try to articulate what the soap is doing to the colors. The soap will pop up from time to time, as it is wittling away, it will pull the colors with it, changing the mixture completely.

Step 10.



As an Extension: with five year olds or older, create a KWL (what they Know, Want to know and what they Learned) chart to find out what they know about color mixing and a "soaps" effect on other substances. As you introduce the activity to the children, add their predictions to the KWL chart or jot them down on a predictions chart; either way, it is important to record their ideas and discuss them later as you process what really occurred. Ask the children "how" and "what" questions to elicit thoughts and ideas. In the very end of the experiment, there is always a point of "saturation" for the color/soap mixture, when the milk is brown or gray and the soap no longer has an effect. Before quitting, try to get a reflection from the students as to why they think this has happened. Their answers can tell you how much they have processed from this activity and how effective this activity was at teaching them a new concept.

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