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Don't just tell your kiddos why leaves change colors, show them! In this week's Saturday Science—courtesy of the Museum of Science and Industry in Chicago—discover what makes fall leaves so colorful.
Materials
- Various types of leaves in different colors
- Small cups
- Coffee filters cut into strips
- Nail polish remover
- Pen
Safety note: Nail polish remover is flammable; do not use near heat. It also is harmful if ingested.
Process
- Tear each leaf into small pieces. Put the pieces of each leaf into a cup. Each leaf should get its own cup.
- Pour enough nail polish remover into the cups to just cover the pieces of leaves.
- Label each coffee filter with the original color of the leaf.
- Stand a strip of coffee filter into each cup. Wait for 10 minutes as the liquid travels up the paper.
- Compare. Take the filter paper from the cup and let it dry. Compare the results for all your leaves. How do the pigments differ?
Results
You just carried out chromatography—a method for analyzing complex mixtures by separating them into the chemicals from which they are made. Plant pigments—the coloring in the tissue of plants—play an important role in capturing light for photosynthesis. These pigments give leaves their colors.
- Chlorophyll pigment makes leaves green and allows the plant to capture energy from the sun for photosynthesis.
- Anthocyanins make leaves red.
- Carotenoids make leaves yellow.
In the fall, trees prepare for winter by shutting down photosynthesis. As this happens, the chlorophyll disappears from the leaves. As this happens, the green color fades and we begin to see yellow and orange—colors that have been there all along, but were hidden by the green pigment. Sugars trapped inside the leaves react with light and other chemicals to reveal new colors.
Learn more about why leaves change colors in this Never Stop Asking Why blog post.
