Autumn is a beautiful time of year. Depending on where you live, the leaves of the deciduous trees turn into bright displays of color and then fall to the ground. But how and why does this happen?
As teachers of young children, this color show is a great opportunity to teach them the science of the world around them.
Why do leaves change color?
Plant leaves contain chlorophyll. Through the process of photosynthesis (and yes, you can use these big words), the plant uses the energy from sunlight to produce glucose that feeds it. It’s this chlorophyll that makes the leaves look green.
As the weather changes, the chlorophyll production slows and then stops. What’s left is the leaf’s real color. Depending which of three chemicals are present in the structure of the leaf, you will see red, yellow or orange leaves.
Why to trees drop their leaves?
Do you know why those leaves fall? The tree is protecting itself. When the weather gets cold and freezes, the parts of the tree that carries the nutrients and water to the leaves will freeze and kill the tree. So it drops those leaves and produces new cells where the leaf stems were that harden and protect the tree.
After they fall, if we leave them there, they will decompose and the rain will work them into the soil. These leaves will then serve as a source of food for the tree in the spring.
Looking for a great activity to do that uses this conversation? Go for a walk. Give every child a bag to collect leaves. Talk about the weather and the things you see (what are the squirrels and birds doing? How does the breeze feel on your face?). Ask the children how the leaves feel? What are the textures?
When you get back to class, make a beautiful, collaborate collage to hang on the wall. While they are putting the picture together, you can mention each color. The red leaves have Anthocyanins in them. It’s Beta-Carotene that makes some leaves orange. And the yellow ones have Flavonols (like egg yolks).
So jump on the fall wagon and enjoy the beautiful world we live in!