Turn your autumn walk into a discovery walk
An autumn walk can easily be turned into a discovery walk by exploring the science behind the change of color in tree leaves.
Fall weather has certainly arrived and with it the change of colors in trees. This is the perfect time to take your youngster outdoors and to the forest or local park for a discovery walk. What child does not like to run through a layer of fallen leaves on a brisk, sunny autumn day? You will find leaves in a variety of shades of color from yellow to orange, red and deep purple and of course green and brown. Take this opportunity a step further and explore with your child the science behind the change of color in leaves. Why are they turning color?
To show off their colors, each leaf needs pigments. As the United States Department of Agriculture (USDA) Forest Service explains, there are three types of pigments that are involved in fall color:
- Chlorophyll, which gives leaves their basic green color. It is necessary for photo synthesis, the chemical reaction that enables plants to use sunlight to manufacture sugars for their food.
- Carotenoids, which produce yellow, orange and brown colors.
- Anthocyanins, which give leaves the red color. They are water soluble and appear in the watery liquid of leaf cells.
While all pigments are present during the growing season, the green chlorophyll is pre-dominant and constantly produced to manufacture sugars. In the fall chlorophyll production slows down and eventually ceases. The carotenoids and anthocyaninsthat are present in the leaf are now unmasked and show their colors.
Why do leaves fall off the tree? As it gets colder in the fall the tree prepares for winter. A thin layer of cells grows over the water tubes in the leaves and closes them up. When the tubes are completely closed the water supply is cut off and the leaves dry out and drop off the tree.
Enjoy the outside walk with your child. Look at the different shapes of the leaves; discover what compound leaves and what simple leaves are and how to identify a tree. Your child may wonder why do some trees stay green and others don’t? Grab the opportunity and find out with your child what deciduous and what coniferous trees are.
Turn your walk outside or even just the chore of raking leaves into a discovery. The opportunities for small science lessons are endless.
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