The problem of the diversity of pupils has gained new dimensions in the last decades. The paradigm of “inclusion” and new intercultural mindsets highlight the diversity of all people independent from traditional categories like handicapped, migrant, poor-gifted etc. Nevertheless, research shows that processes in society like the new accountability-measures implicate a systematic marginalization of disadvantaged pupils (cf. Hopmann 2008, Hörmann 2007) which leads to the question, at which point the heterogeneity of pupils is regarded as a resource and in which context it appears to be a burden (cf. Douglas 1969). As the society and its teachers see themselves confronted with new challenges concerning pupils with migration background or children with special needs, one has to ask what this new challenge is about and how it can be described empirically: What impact does the heterogeneity of pupils have on instruction? In how far can the diversity of pupils be regarded as a resource for teaching? When do people think that heterogeneity becomes a burden? The mixed-methods-design will enlighten teaching processes and their possible contribution to problem-solving capacities of schools in a Norwegian-Austrian comparative view.