1-2 stalks of fairly fresh lettuce for each participant
1 drinking glass per participant, preferably clear
Food coloring (drops, NOT gel - blue or red work best)
Thinly slice off the bottom of each celery stalk to reveal fresh plant. Fill up the glass with water - about 1/2 way. Then put 5-10 drops of food coloring into the water and stir with a spoon.
Have student write down what they have done so far, and draw and color a picture of what their celery looks like 'before'. Have them create a hypothesis of what might happen to the celery after 24-36 hours in the cup.
Place the stalk(s) of celery into the water, making sure that the leaves are sticking out of the water.
Place on a shelf where they will not be bothered for 24-48 hours.
Later come back and check out the plants. They should have obvious coloration extending up the celery stalk - even the portion that was not submerged in the water should be streaked with color. At best, the leaves will also show coloration.
Talk about how water is sucked up through channels in the plant, and then delivered to the leaves. Explore plant root systems and view images of various roots.
Take it further by going on a nature walk and discuss the type of root systems various plants have and how they would distribute water internally like the celery did.
Finally have students determine if their hypothesis was correct and to draw a new picture of what their celery stalk looks like (with color!) and write a description as well.
This Carnation-Color-Change experiment is a great idea for how to take the learning further...and something I think we will do once carnations are back in season!