In December 2015, the Principia mission was launched and many schools took part in local or national activities associated with the Principia mission. Researchers at York undertook a three-year study to find out about the influence of human spaceflight on children's attitudes towards STEM subjects. Along with a large-scale survey, between November 2015 and July 2017, the authors interviewed children and teachers in primary schools across England to find out what their experiences were and to identify factors that facilitated or impeded engagement with STEM subjects (science, technology, engineering and mathematics), and space in particular. The authors identified factors within four spheres of influence: the national and cultural, home and community, school and individual. This article focuses on school-level factors, which are likely to be of interest to those involved in primary science education. In the nine case-study schools the authors visited, five main school factors shaped how children experienced learning about STEM, and space in particular. These were school leadership, the role of teachers and other key educators, how the curriculum was taught, extracurricular opportunities and relationships with STEM experts.