The role of mathematics in STEM teaching is often described as limited or unclear, and more or less always conceived as a tool. This paper examines the role of mathematics in 19 STEM activities developed in the research and development project LabSTEM, the goal of which includes developing STEM activities where mathematics is the focal point. All 19 activities include mathematics, and they target students from kindergarten to lower secondary school. The analysis contains a categorisation of the different roles that mathematics plays in the 19 STEM activities. The results show that teachers manage to present mathematics not as abstract and decontextualised but as integrated and relevant in most of the 19 activities. Nevertheless, there is a persistent tendency for them to place mathematics learning in the background, relegating mathematics to a supporting role in STEM.