In this two-part activity, high school biology students examine human karyotyping, sex-chromosome-linked disorders, and the relationship between biological sex and gender. Through interactive simulations and a structured discussion lab, students create a human karyotype and diagnose chromosomal disorders in hypothetical patients, as well as formulate a scientifically based argument distinguishing biological sex from gender. This activity reinforces biology concepts such as DNA structure and function, meiosis, and the inheritance of traits. In their arguments, students integrate prior knowledge with science content. This lesson connects the world of science with issues important in their own lives.