How we did it:
- glass jar
- food coloring
Step 1: Cut about 1 inch from the bottom of the celery stalk.
When I told H we were going to do a celery experiment, he was ready to get chopping! After a bit of thought, I decided to let him cut the veggies himself. The lesson turned out to be a good one in knife safety! He was feeling like such a big boy.
Step 2: Add food coloring to a glass of water.
Next he added food color to water and watched wide-eyed as clouds of primary colors swirled around in the clear liquid. Though a simple action, it's a nice way to introduce the concept of density since the dye sinks to the bottom of the glass.
Step 3: Soak the celery in the dyed water.
Step 4: Wait about 20 minutes, and then start checking the celery!
I was attempting the best way to photograph the teeny dots of color from the end of the stalk, when H grabbed a stalk, ripped it open, and clearly exposed the inside of the celery.
Step 5: Check back on your celery stalks in about an hour -- the dye should have made its way to the leafy green tops!
After about an hour, the dye had made its way into the leafy green tops. I set it on the table so H could discover the change on his own. When he did, he was thrilled and excitedly explained to Dad, "The blue water got to the leaves because of the teeny tiny tubes sucking the water up like a straw!" If you leave the celery in the dye overnight, the leaves get almost completely saturated by color. We were all amazed by the vibrant blue-colored leaves.
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.