So Yeon, first year into middle school, spends all her lesson money behind her mother’s back to buy a guitar for the ‘guitar guy’ she has a crush on. Convinced by her beloved, who is in his third year of high school, So Yeon proposes a ‘sexual experiment in the biology classroom’ to another male middle school mate. Lesson is a short film that addresses the sexual inquiries and fantasies of a teenage girl as well as her right to decide on her own sexual inclinations.