Why do tree leaves change colors in autumn and then fall off?

Tree leaves change colors and fall off because they get ready for winter, just like you get ready for bed when it's time to sleep.

In summer, leaves are green because of a special helper called chlorophyll. It helps the tree eat sunlight. But when days get shorter and colder, the tree starts to say, “Time for rest!” The chlorophyll gets used up, and other colors, like yellow, orange, and red, come out to play. That’s why leaves look so pretty in autumn.

Once the tree is ready for winter, it stops sending food to the leaves. Without food, the leaves get tired and loose their grip on the branches. They shake off, just like you let go of a toy when you're done playing with it. Then they fall to the ground, making a nice cozy blanket for the tree during the cold months.

It’s like your tree is taking a long nap, and the leaves are helping it get ready!