2016 No https://doi.org/10.1111/ina.12210 Peterson, S. Europe Experimental Students Elementary (K-5) Ventilation rates Carbon Dioxide (CO2) Test Performance Cognative function Indoor environment Carbon dioxide (CO2) Children Performance Double-blind crossover study in Danish schools measured how increased ventilation (lower CO₂) affects test performance in 10–12 y.o. students. Higher air supply improved all four academic tests. Supports policies enhancing classroom air quality to boost learning outcomes.