This study is a thesis project for the program Civilingenjör och Lärare at KTH. The study was conducted in spring 2014 in collaboration with Komplementskolan AB which has developed the educational material Studi.se, the focal point of this study.The overall aim of the study is to increase the knowledge of the participant teachers? conception and use of the educational material Studi.se. The second purpose is to increase knowledge about the forms of use some of these teachers apply or claim to apply when using Studi.se. Theoretical framework used is constructivism and the notions of Piaget: adaptation, assimilation and accommodation.