In autumn, many leaves change from green to yellow, orange, or red. This is one of the most beautiful signs of nature.
But why does this happen? The answer is in a special material called chlorophyll. Chlorophyll gives leaves their green colour. It also helps the tree make food from sunlight.
When autumn comes, the days become shorter and there is less sunlight. The tree starts to rest. It stops making chlorophyll. Without chlorophyll, the green colour goes away.
Then we can see the yellow and orange that were hidden inside the leaf all year long. Some leaves also turn red because they make a new material in the cold night.
So, the beautiful autumn leaves are not just pretty to look at. They tell us a story about how trees prepare for the long, cold winter.