Three lesions: a scrapable white patch, a velvety red patch, and rupturing blisters. How does the student triage? Scrapable white suggests candidiasis (treat the fungus); velvety red suggests erythroplakia (urgent biopsy - highest malignant potential); rupturing blisters with Nikolsky suggest pemphigus (biopsy plus immunofluorescence, dermatology referral). Students learn mucosal triage: identify the category by behaviour (scrapable? blistering? red?), then apply that category's rule - because each family has its own urgency.