An important aspect of teaching biology is to expose students to the concept of biodiversity. For this purpose, bacteria are excellent examples. The advanced placement (AP) biology class at Cedar Shoals High School in Athens, Georgia, learned how to explore bacterial biodiversity using molecular fingerprinting. They collected marine water samples, isolated bacterial colonies, extracted DNA, amplified and sequenced the 16S rRNA genes, and then compared the sequences to an Internet database to reveal the identity of the isolates. The project began with a field trip to the salt marshes on Sapelo Island, a barrier island in coastal Georgia, and was completed at their high school and in a laboratory at the University of Georgia. In this article, the authors describe how the bacterial biodiversity exercise was carried out, and discuss options for source material for bacterial isolation and flexibility in scheduling the laboratory exercise modules. (Contains 1 table and 1 figure.)