Biological terms describing abnormal numbers of chromosomes, such as polyploidy, eupolyploidy, aneuploidy, autopolyploidy, and allopolyploidy, can be confusing to students. A card-sorting activity designed to expose high school students to these key terms used in the evolution and genetics units of biology classes allows them to visualize these concepts. Students work with classmates to organize key terms with matching definitions and diagrams. The activity will solidify students' knowledge and understanding about different chromosomal abnormalities that can result from nondisjunction occurring in meiosis or from mating with different species, which may lead to sympatric speciation. The culmination of the activity includes students using their inquiry-based skills to investigate mystery plant and animal cards and determining if they are autopolyploid or allopolyploid organisms.