Are spiders related to crabs? Study the order of arthropods with a reading selection about animal diversity. It provides details about each class within the order, as well as vivid pictures and explanatory charts. 

These pages are part of a site called Evolution that accompany a textbook by the same name. Mark Ridley is the author. In this section: the universal genetic code provides evidence that life has a common ancestor.

Visit some of the biggest questions that scientists try to answer about evolution.

By examining fossils, scientists have collected evidence that supports the theory that species changed over time. As you read this article, study this evidence and critically evaluate whether it indicates that species may have arisen by...

These pages are from the Understanding Evolution website for teachers. They focus on homologous structures that organisms with common ancestors share.

A textbook definition along with an explanation of the scientific theory of evolution.

Explains that analogous structures are ones that are similar in different organisms yet have no common ancestry. This type of phenomenon occurs with convergent evolution. Includes lots of examples for both animals and plants.

Provides a student handout in PDF format that looks at the developmental stages of five vertebrate organisms from fertilization to adult form. Students can look at the pictures to see the similarities and differences at the embryo stage...

Charles Darwin was born in England on February 12, 1809. He was a "naturalist," best known for his theories of evolution. Darwin collected evidence that all life on Earth "evolved" from a common ancestry. He studied the process of...