During one of our recent class discussions about life cycles, a student asked how water 'feeds' plants, more specifically, how water gets to the top of the plant. They linked strength to water deciding that water must have muscles therefore it had the ability to go up all the way to the top of the plant and 'feed' it. So, while that is a fantastic guess, this was a perfect opportunity to do the classic celery and food colouring experiment. This experiment is a great demonstration of how water travels up the stem (or in this case the stalk) all the way up to the leaves nourishing the plant with one of the vital components of life...water. The food colouring would be the indicator, of course. We'll cut the celery and take a closer look at where the coloured water traveled and talk about the science behind it. We may just have to bring in some microscopes!
The Science: Tiny tubes draw the water up from the roots like a straw. The water molecules go up the tiny tubes and move towards 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. Pretty cool!
To the right is our Scientific Experiment Worksheet that each student will fill out independently.
Below are a few before pictures, after pictures to follow!