The evolving nature of the Japanese lexicon in a tradition of lesson study

The Japanese tradition of lesson study has created a teaching community in which observation and discussion of classroom teaching are integral parts of professional practice. Within the community a system of pedagogical terms and phrases has been developed and shared through the practice of studying and improving classroom teaching. This chapter reports on the results of research that explored the constituent elements and structural characteristics of the Japanese Lexicon as a part of The International Classroom Lexicon Project. We created a lexicon of 70 lexicon items with their entries focusing on forms and functions of participants’ action. The process and the result of developing a lexicon are outlined. A questionnaire and electronic survey were conducted, respectively, for a local and national validation to examine how familiar the lexicon items were for the mathematics teachers in Japan. We discuss that the Japanese Lexicon can be characterised by its evolving nature and that some of the lexicon items can be seen as value-laden items derived from the practice of lesson study.