Classrooms, which were once a place of safety and stability, have changed in many ways due to the COVID-19 pandemic. They have been deep cleaned, rearranged, closed, reopened and, for many, moved online. But just how does the classroom environment impact on pupils' health, wellbeing and ability to learn? Ground-breaking research by Professor Stephen Heppell and his team is shining a light on the impact of classroom environmental factors on pupil performance. These factors are often overlooked when attempts are made to improve outcomes for pupils, and getting to grips with them has never been more important. Professor Heppell's research focuses on seven key factors that influence learning. This article shares the seven key factors that influence learning, guideline levels, and simple remedies for the classroom. It also shares suggestions for virtual classrooms and outdoor learning environments.