We followed the story with three experiments dealing with color. After dropping food coloring into a shallow pool milk, we dipped a dry cotton swab into it and observed the results.
After adding dishwashing liquid to the swab - look what happened!
Certain molecules of the soap dissolve in the watery portions of the milk while others attach themselves to the fat in the mik. Evidence of this attachment is what we see when the colors look to be moving out to the edges of the circle.
Next we banded squares of cotton to the top of a cup for an experiment with "permanent" markers. We drew small multicolored dots with Sharpie markers, the added just a drop of isopropyl alcohol atop the design. As the alcohol spread out in a circular fashion, it took the color with it - instant tie-dye!
We had very little time for our final experiment. We cut a strip from a coffee filter, drew a line at the bottom with a water soluble black marker, then placed the filter along the side of the cup with a little water in the bottom. As the water climbed up the filter, the black of the line changed to varying shades of blue. What do you think might have happened if we'd had more time and could observe longer?