When I found out Juju was learning about plants in Kindergarten, I decided we would perform a little experiment that I remember from my childhood. It's an oldie, but a goodie that demonstrates how plants move water from roots to leaves.
I began by choosing a celery stalk with lots of leaves and trimmed the end. Starting at the cut end, I made a slice approximately six inches long through the center of the stalk.
Next we filled two juice glasses about halfway with water. We added red food coloring to one, and blue to the other (approximately 20 drops of food coloring in 1 cup of water).
We placed one side of the split celery stalk in the red glass and the other side in the blue. At this point I asked Juju to make a prediction. She predicted that the leaves would turn purple because the red and blue food coloring would mix together in the leaves.
The next morning we examined the celery. Juju was perplexed when she observed that the leaves were red on one side of the stalk and blue on the other, not purple as she expected.
I asked her to give me a minute so I could show her what happened to the food coloring. I cut a slice of stalk above split.
Then we examined the cross-section.
I explained to her that plants have tiny tubes called xylem which carry water from the roots to the leaves. The food coloring dyed these tubes as it moved through them and it dyed the leaves when it reached the end of the tubes.
I also mentioned that plants use sunlight to make their own food. This food, a sugar, is carried from the leaves to the rest of the plant in another kind of tube called phloem.
With that, Juju asked if we could try it again with more colors. Anyone who peeks into my compost bin is in for a little surprise because it is full of rainbow colored celery stalks!