This lesson provides three activities to engage non-science major students in a discussion about sex, gender, gender identity, and sex determination. Students prepare for the lesson by reading a short article titled Sex and gender: What is the difference? and responding with research topics that would be most appropriate for one term over the other (sex vs. gender). This forms the basis of the first activity in which students brainstorm what it means to be female or male, and then identify whether each idea is related to a sex or gender characteristic, followed by a whole class discussion. The second activity is a clicker question with four published journal article titles, and students identify which is the least appropriate use of the term gender. The final activity involves a case study of María José Martínez-Patiño who failed a sex test in 1985 and was denied the right to compete as a female in the World University Games. In the case study, students grapple with the physiology of androgen insensitivity and what ultimately determines a persons' sex and gender identity. Non-science major students find these activities accessible and engaging, and each activity serves as a formative assessment for both the teacher and student. Summative assessments evaluate the students' level of confidence related to each of the three learning outcomes, and their understanding of terminology, context, and examples of sex and gender.