This study reports on an investigation of teacher interventions in students' collaborative work in an educational makerspace. We draw on a qualitative analysis of video data on teacher-student interaction derived from 94 students (aged 9-12) and their teachers in a Finnish school. The results show that the teacher interventions were both student- and teacher-initiated. Three leading teacher intervention strategies were identified, namely authoritative, orchestrating and unleashing which emerged in teacher-student interactions dealing with conceptual, procedural, technological, behavioural and motivational issues. The study demonstrates the demands makerspaces pose for teacher-student interaction, and how moving from authoritative to collaborative interaction requires collective efforts and cultural change.