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

* The rock is still the same type of rock, just in smaller pieces.

* No new substances are formed.

* Chemical Change: A change where a new substance is formed with different chemical properties.

* Examples: Burning wood, rusting iron, cooking an egg.

Think of it this way: You can put the small pieces of rock back together to form the original rock. This wouldn't be possible if a chemical change had occurred.