The American Geological Institute has done an excellent job of defining and explaining evolution in this online booklet. Darwin, fossils, natural selection, and change over time are some of the concepts that are covered. Make sure to see...

Understand fossils and the fossil record as it relates to Earth's history.

This site from BioWeb Evolution was originally created as a ThinkQuest entry, and it has some good basic information about evolution. This page is on fossils and geologic time.

Find out how scientists can find out the age of the rocks they are studying.