Backpack Science with Ken Finn: The Rainbow Explosion

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Backpack Science

Backpack Science is a summer series of easy at-home experiments geek dads can perform with their kids while school’s out. It is written by (San Francisco) Exploratorium science educator Ken Finn. This article is #3; you can find the whole series here.

The Rainbow Explosion

I was a geek long before I was a dad. Before I had a family of my own, I used to do this activity during breakfast. In fact, I thought it was so cool that I would show it to people at dinner parties. Like I said — total pre-dad geek. Now that I have children, I enjoy sharing this amazing exploration of swirling color with my daughters. It’s both beautiful and fascinating.

What you’ll need:

  • whole or 2 percent milk
  • saucer
  • food coloring
  • cotton swab
  • rubbing alcohol

How it’s done:

  1. Pour about ½ inch (1 ¼ cm) of whole or 2 percent milk into a saucer. Let it come to room temperature.
  2. Plop several drops of different food coloring onto the milk’s surface. They might spread a little, but they’ll stay where you put them.
  3. Soak the end of a cotton swab in rubbing alcohol. Touch it to the color drops, which will explode into wild whorls and bursts.

The Rainbow Explosion, excerpted with permission from Exploralab, 2013, published by Weldon Owen © Exploratorium, All Rights Reserved.


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