Abstract: This article presents a case study of middle school student Xiaohua Zhuang, who experienced sudden acne breakout prior to a speech competition. Through chemical experimentation and analysis, Xiaohua learned about proper skincare practices, including maintaining skin pH balance, the significance of gentle cleansing, and correct sun protection. Presented in narrative form, this work elucidates the chemical mechanisms of cleansing and sunscreen products while addressing common skincare misconceptions. The study provides adolescents with scientifically grounded yet engaging skincare guidance, demonstrating the practical applications of chemical knowledge in daily life.

Key words: Cosmetics, Cleansing products, Sunscreen products, Physical sunscreen