This study investigates how teaching in half-size classes compared to full classes impacts Swedish music teachers’ reported experiences regarding work environment, relations, well-being, and student outcomes. Based on a questionnaire with 541 teachers (Years 4–9), findings show teachers with half-sized classes report significantly better conditions across almost all aspects. However, no corresponding difference was found in student pass rates. Interpreted through frame factor theory, these results suggest that while smaller classes improve the educational environment, these qualitative benefits are not reflected in grades, raising implications for policy.