Schools are the places where children spend the most time outside of their homes. Air quality in these spaces is therefore crucial not only for their health but also for their learning. Shortly after its creation in 2001, the Indoor Air Quality Observatory (OQAI) launched a program dedicated to buildings that house children. This article aims to summarize the work conducted, in light of the questions that have arisen regarding ventilation in schools during the COVID-19 pandemic. The results of the OQAI’s work consistently reveal a problem of insufficient air exchange in classrooms in France and, consequently, often poor indoor air quality. Solutions exist to encourage the opening of windows in schools not equipped with a mechanical ventilation system. Reducing sources of indoor pollution is also a major lever for improving air quality in enclosed spaces. In general, raising awareness among children, teachers, and school building managers should be promoted.