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You may have experienced a tree turning from green to yellow during the fall. But did you know that the yellow colors that suddenly appear were actually in the leaf the entire time?
It’s true! The green chlorophyll we see most of the year masks the yellow color, which can only be seen in the fall when the chlorophyll breaks down.
In this post I’m sharing a simple but effective hands-on activity I did with my kids to drive home the point that the yellow color that appears in the fall has actually been in the leaf the whole time.
Note: For more leaf activities, see my Botany Unit Study page.
The science behind how and why leaves change colors
When my kids and I did our leaves unit study, we did a chromatography experiment to understand why leaves change colors. At that time, we read books about leaves and watched several videos explaining why leaves change colors.
Here are the three videos we watched:
- Why do leaves change color in the fall? from DNews
- Why do autumn leaves change color? from Scientific American
- Why do leaves change color in the fall? from Super Scienced
From these videos we learned that the green color in leaves is from chlorophyll, which is what leaves use to make their own food. As the days get shorter in autumn, trees sense that winter is approaching. Because their leaves would not survive the cold, dark days of winter, deciduous trees decide to let their leaves go. Therefore, deciduous trees stop producing new chlorophyll.
The chlorophyll already in the leaves breaks down, revealing the other pigments inside the leaves that were previously masked by the green chlorophyll, particularly yellow and orange. (In contrast to yellow and orange pigments, red pigments are actually created after the fact when sugars in the leaves react with other chemicals to form the red pigments.)
Location, elevation, temperature, sun exposure, and nutrient content of the soil all have an impact on the color the leaves will turn. Thus, the leaves on a tree may turn yellow one year and orange another.
A hands-on activity showing why leaves change colors
After doing our chromatography experiment to understand why leaves change colors, I was looking for another way to really drive home the point that the yellow colors are present all year long, but only revealed when the chlorophyll breaks down.
I ended up creating a printable activity that demonstrates why leaves change colors in the fall. (Grab your free copy of this printable at the end of the post.)
Here is a sneak peak at the four pages included in my Why Fall Leaves Change Colors printable activity:
After explaining to my kids why leaves change colors, I handed them the leaf I had colored green. I told them the leaf was green because it still had all its chlorophyll, but fall was coming and the chlorophyll was starting to break down.
I then invited them to use the white board eraser to “break down” the chlorophyll.
I literally heard squeals of delight when my kids noticed the yellow color under the green!
Once the “chlorophyll” was all gone, the beautiful yellow color was revealed.
The kids had so much fun, they had me color the leaves green again so they could do the activity a second time.
But more importantly, this activity really helped them understand the process by which leaves turn colors in the fall.
Want a copy of my Why Leaves Change Colors in the Fall activity?
Get it as part of the Fall Printables Bundle.
Or get it by clicking the button below.
More resources for learning about leaves
More leaf posts from Gift of Curiosity: