a paper towel just wicks up moisture, which demonstrates capillarity. You can do the same thing with the old favorite of putting a freshly-cut stalk of celery in a couple inches of colored water, & see the color rise to the top. Or use carnations.
You can also use a paper coffee filter. cut it in an arrow shape & put a dot of felt-tip marker (black, purple, or green) abt 1" from the end. suspend the arrow over a jar w/ abt. 1" of water in it; the tip of the arrow only should be in the water -- not the ink spot -- & then watch as capillarity pulls the colors out of the ink & deposits them along the filter. Cool.
Not descriptions, but demonstrations, which speak louder than words.
