In this case study, students learn about intersex through the lens of Dana Zzyym, an intersex activist known for advocating for intersex visibility and for campaigning to include “X” as a valid sex designation on passports and other legal documentation. Students engage with Dana’s story while learning key concepts related to sex designation and gamete production. They then investigate the physiological diversity of intersex variations by researching different conditions and their characteristics, applying this knowledge to what they know about Dana’s story. Students further extend these concepts to examine the presence of intersex individuals in society and how intersex is addressed in legal and medical contexts. By the end of the case study, students are expected to understand the biological basis of intersex, how it presents in humans and other organisms, and the range of societal interpretations surrounding it.  Originally developed for an undergraduate endocrinology course, this case study could easily be adapted for a general human physiology, biology, or science and policy course.