This paper provides a detailed analysis of the work of the teacher during collaborative-learning activities. Whilst the importance of the teacher for the success of collaborative learning has frequently been recognized in the CSCL literature, there is nevertheless a curious absence of detailed studies that describe how the teacher intervenes in pupils' collaborative-learning activities, which may be a reflection of the ambivalent status of teachers within a field that has tried to transfer authority from teachers to pupils. Through a close analysis of different types of teacher interventions into pupils working in pairs with a storyboarding tool, this paper argues, firstly, that concerns of classroom management and pedagogy are typically intertwined and, secondly, that although there may be tensions between the perspectives of teachers and pupils these do not take the form of antagonistic struggles. The paper concludes that it may be time to renew our interest in the work of teachers in the analysis of collaborative-learning activities.