For this experiment, you need 7 clear water glasses or plastic cups, 6 paper towels, water and red, blue and yellow food coloring.
Try it outside so you don't have to worry about spills!
Place glasses in a row, and add water to the first, third, fifth and seventh glasses until they are half full.
Put several drops of red food coloring in the first and seventh glasses of water, and blue and yellow in the other two in whatever order you want.
Fold the paper towels into long, skinny rectangles and place them in the adjacent glasses, half in each one. NOTE: every other glass will be empty! We tried it with putting clear water in the empty glasses and it didn’t work--or you can try that as well and talk about why it doesn’t work!
Watch for a while as the colored water begins to travel up the paper towels. Try to predict what will happen. After several hours, look to see what color water has appeared in the empty glasses. You can talk about the color wheel, osmosis, primary and secondary colors, properties of liquids, etc. Just for fun, you can try blending other combinations like red and green or orange and blue. Try to predict what colors you will get.
Photo Credit: Incredible Science