This newsletter describes an ongoing empirical field study involving a description and analysis of practical teaching situations aimed at describing the content and structure of pupils' frames of reference. The project takes the form of a series of case studies in classes of the 3-year lines of upper secondary schools in Sweden. The study seeks to determine if these alternative frames of reference occur not only in science but in the humanities and social sciences as well. Another question concerns the understanding of the stability of alternative frames of reference. (CW)