* Physical Change: A change in the form or appearance of a substance, but not its chemical composition.

* Chemical Change: A change that results in the formation of new substances with different chemical properties.

When leaves fall from trees, the following happens:

* The leaves detach from the tree: This is a physical separation.

* The leaves decompose: This is a chemical process, but it occurs *after* the leaves have fallen. The decomposition itself is a chemical change, but the act of falling is not.

In summary: The falling of leaves is a physical change because it involves only a change in the position of the leaves, not a change in their chemical makeup.