You can see a tree's reflection in still water because the smooth surface acts like a mirror.

Here's why:

* Reflection: When light hits a smooth surface, it bounces back at the same angle it hit. This is called reflection.

* Still Water: Still water has a very smooth surface. Light rays bouncing off the surface are reflected in a predictable way, creating a clear image of the tree.

* Disturbed Water: When the water is disturbed, the surface becomes uneven. Light rays hitting the water bounce off in different directions. This scattering of light makes the reflection blurry and difficult to see.

Think of it this way:

* Still water is like a perfectly flat mirror.

* Disturbed water is like a broken mirror.

Let me know if you have any other questions!