Try beet watercolor for a snack and activity in one! 

First, peel and chop a beet.

Place in a microwave safe bowl, then add enough water to cover.

Microwave until soft, then pour off the brightly colored water.

Give kids a piece of paper (heavyweight if you have it), and a paintbrush. Older kids can make a pattern with tape before painting. 

Use the beet water as your paint, and eat the beets!  After the paper has dried, remove tape (if used) to reveal the white pattern.
For more beet-related fun, click here for a video of Katherine Ayres reading her book "Up, Down, and Around".