How do students learn to explain? We take this exemplary research question for presenting two antagonist traditions in German mathematics education research and their synthesis in an ongoing video study. These two traditions are (1) the German Didaktik approach that can be characterized by its epistemologically sensitive analyses and…

Drawing on sequential and multimodal analysis of video-recorded classroom interactions, the paper examines in detail the interactional practices and verbal and bodily displays that serve to (re-)establish a congruency between the teacher's expectation with regard to the participants' relative knowledge and the students' actual knowledge claims. By…