Evolution is commonly taught as a slow process that changes gene frequencies over long time periods. These genotypes are changed through natural selection on phenotypes with the fittest individuals spreading more genes into the environment than less-fit phenotypes. What is now well known to science, but still under-emphasized in textbooks and classroom lessons, is that humans can be one of the strongest selection agents on an organism's phenotype through several different pathways. Humans have perhaps the longest history of affecting organism phenotypes through size-selective harvest, or collection of the largest organism. This activity was designed to supplement traditional evolution units and allow students to discover that evolution can occur in relatively short time-periods and be directed by human action. After completing this activity, students will be able to: (1) predict the consequences of selective harvesting; (2) understand how evolution and natural selection affect genotypes and phenotypes; (3) design and critique experimental design; (4) collect and analyze data; and (5) make conclusions based on research results. (Contains 4 figures.)