Directions: Fill cups/jars half-full of water. Add 5-8 drops of food coloring to each cup/jar. Cut the bottom of the celery to make each stalk the same height (use the stalks with some leaves on them). Place celery into cup/jars. Observe the changes several times over a 24-48 hour period.
The science: When you water the soil of your plants, how does the water travel from the soil into the plant and out to the leaves? Tiny tubes (xylem) draw the water up from the roots like a straw. It works by a capillary action. The water molecules suck up inside the tiny tubes and move up and out to the leaves as if someone was sucking on the end of the tubes. The suction actually occurs as a result of water in the leaves evaporating very slowly.