We designed a teacher development programme and implemented it with eight teachers who participated in it over the course of either the 2013/14 school year (four teachers) or the 2014/15 school year (four teachers). During the programme, the teachers were trained in ways to transform their practice, while the transformation process was monitored within the framework of our research. We made video recordings of all participating teachers before starting the programme and again after completing it. Comparative analysis of video recordings before and at the end of the programme allowed us to establish whether there had been a change in classroom discourse. Subsequently, we started to examine the developmental trajectory of change identified in individual teachers' practices. The fundamental finding was that the change was not linear in the sense that there would be a gradual rise in indicators. We noticed a succession of phases of acceleration of change with phases of stagnation and regression. We are currently using the quantitative method to describe the subtle details of this change and to explain its development.