Why do trees drop their leaves?

Leaves are like tiny factories that make food for a tree. A green stuff called chlorophyll catches sunlight and turns it into food for the tree. But when the weather gets cold, there is less sunlight, and the water in the soil starts to freeze.

The tree takes steps so it doesn't lose water through its leaves. In autumn, the water and food going to the leaves are slowly cut off. When the chlorophyll fades away, the yellow and red colours hiding under it show up.

At last, the leaf's little stem gets weak, and the wind blows the leaf to the ground. This way, the tree can rest all winter without using up energy, and it keeps its water safe.

Not every tree drops its leaves. Trees with needle-like leaves, like pine trees, can keep their leaves even in winter, because they lose much less water.