The ethnography of education is challenged by the materiality of the classroom. Ethnographic accounts of school lessons mostly highlight language and interaction and offer no suitable methodology for researching objects and their role in the classroom. Moreover, objects are part of complex and interwoven assemblages involving human actors, practices and things. As such, their contribution to human practices often remains unnoticed in the background of routine activities. In order to make the materiality of practice available to ethnographic observation, we thus have to analytically disassemble these assemblages. An ethnographic approach that draws on practice theory and concepts developed in science and technology studies is proposed. Three analytic strategies dealing with the materiality of education are introduced and discussed on the basis of examples from an ethnographic research project on the role of knowledge objects in mathematics and physics classes in German secondary schools. (Contains 7 notes and 1 figure.)