Moving beyond the basic concepts of autosomal Mendelian inheritance to sex-linkage can be difficult for introductory biology students. Although crosses with Drosophila fruit flies have long been a mainstay of genetics units that teach these concepts, they can be unwieldy for large numbers of students, take much of a semester to complete, and require substantial preparation time. We developed a guided exploration laboratory activity that illustrates the contrasts between sex-linked and autosomal …