The seven lessons in this unit give students the opportunity to consider the evidence that prompted Charles Darwin to reach the conclusion that natural selection is the mechanism of evolution. Students will learn how genetic variation and environmental factors cause diversity to develop within populations. They will examine the geological and paleontogical evidence that supports the theory of evolution by means of natural selection. They will also examine evidence from the field of comparative anatomy supports the theory of evolution.Students will be able to show how are living things classified to show the relationship of the various living kingdoms and what happens to a species when the adaptations of its members cannot assure their survival in the face of environmental change. STUDENT WORKSHEETS, an EDUCATOR GUIDE, and the UNIT TEST for assessing student performance after completing this unit are included.