This thesis reports results from a study that focuses on teachers’ professional development during an in-service training period.   The aim is to analyse and describe how the teachers talk about and handle lesson content. The first question concerns changes in relation to a specific object of learning. The second question concerns how they relate to a theoretical framework and the third question concerns differences in the students’ learning outcome and if it can be understood in relation to the teachers’ development.   The variation theory is the theoretical framework that is used for lesson planning as well as when analysing results. The basis of the study is that learning always is the learning of something and that the teachers’ activity as well as the students’ activity constitutes the space of variation that decides what is possible to learn concerning a delimited object of learning, i.e. the enacted object of learning. The object of learning is seen as a capability and it can be defined by its critical features. The constitution of the meaning aimed for the critical features of the object must be discerned. The intentional object of learning describes the teachers’ intention with the lesson, and the lived object of learning is what the students really discerned. The theoretical assumption is that learning always assumes an experienced variation where learning is seen as a change in the learners’ possibility to experience the world in a certain way. You have to have experienced a phenomenon’s variation to understand its meaning, i.e. what we experience is how something differs from something else.   The method is Learning study and it can be described as a hybrid of the Japanese Lesson study and Design experiment. A Learning study is theoretically grounded and the primary focus is on an object of learning. The learning study group consisted of three teachers and most often two researchers. Each member had equal status in the group. The object of learning seen from the teachers’ perspective was the variation theory that was gradually introduced by the researchers. The empirical material was generated from audio-taped discussions and from videotaped lessons.   The findings should be seen as a contribution to the discussion about teachers’ professional development. The teachers participated in a collective construction of professional knowledge and it can be stated that the teachers had no problem changing their discussions to focus on a specific object of learning when the theoretical framework was used in relation to their own practices. Another finding is that the change in how the teachers handled the object of learning influenced the students’ learning in a positive way although the results were subtle.

This thesis reports results from a study that focuses on teachers’ professional development during an in-service training period. The aim is to analyse and describe how the teachers talk about and handle lesson content. The first question concerns changes in relation to a specific object of learning. The second question concerns how they relate to a theoretical framework and the third question concerns differences in the students’ learning outcome and if it can be understood in relation to the teachers’ development. The variation theory is the theoretical framework that is used for lesson planning as well as when analysing results. The basis of the study is that learning always is the learning of something and that the teachers’ activity as well as the students’ activity constitutes the space of variation that decides what is possible to learn concerning a delimited object of learning, i.e. the enacted object of learning. The object of learning is seen as a capability and it can be defined by its critical features. The constitution of the meaning aimed for the critical features of the object must be discerned. The intentional object of learning describes the teachers’ intention with the lesson, and the lived object of learning is what the students really discerned. The theoretical assumption is that learning always assumes an experienced variation where learning is seen as a change in the learners’ possibility to experience the world in a certain way. You have to have experienced a phenomenon’s variation to understand its meaning, i.e. what we experience is how something differs from something else. The method is Learning study and it can be described as a hybrid of the Japanese Lesson study and Design experiment. A Learning study is theoretically grounded and the primary focus is on an object of learning. The learning study group consisted of three teachers and most often two researchers. Each member had equal status in the group. The object of learning seen from the teachers’ perspective was the variation theory that was gradually introduced by the researchers. The empirical material was generated from audio-taped discussions and from videotaped lessons. The findings should be seen as a contribution to the discussion about teachers’ professional development. The teachers participated in a collective construction of pro-fessional knowledge and it can be stated that the teachers had no problem changing their discussions to focus on a specific object of learning when the theoretical framework was used in relation to their own practices. Another finding is that the change in how the teachers handled the object of learning influenced the students’ learning in a positive way although the results were subtle.