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

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.

The Tiv are a group of about a million people who live on both sides of the Benue River, 220 kilometers from its confluence with the Niger, in Nigeria. "Tiv" is the name of the common ancestor from whom all are descended. There is a...

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...

Explains what homologous structures are and how they indicate common ancestry between species. Discusses morphological homology, which refers to anatomical and skeletal similarities, and molecular homology, which refers to common...

This is a collection of 24 Grade-Leveled texts (5-11) on the topic of Immigration. Most Americans can trace their ancestry back to immigrants coming to the New World. Learn about America's history of immigration, particularly during the...

There are more than five hundred different species of skates and rays in our oceans. Scientists say that these fish are closely related to sharks, sharing a common ancestor from around 400 million years ago. This article provides an...

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.

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...

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

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

Explains how the eyes of very diverse species have a common genetic ancestry.

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...