There are three aims concerning the article. One aim is to investigate teachers´ and pupils´ involvement in a learning study and to discuss the involvement of teacher students. There is also an aim for a research project to investigate integration of general teacher knowledge and subject knowledge in the learning study. The third aim is to improve pupils´ learning in the learning study. The results show that the teachers are involved in the learning study but not in the research process as a whole. Pupils are not involved more than according to if they want to participate. The teachers did integrate critical thinking with mathematic didactic, but not in a systematic way. The pupils´ learning developed in the learning study and the analysis ought to be systematic developed at an individual level for more differentiated results. According to the teachers´ knowledge that was showed in the learning study it would be appropriate to use learning study for supervision of teacher students.