Resumen

This work aims to investigate the development of reflection on the practice in the training of mathematics teachers through the design and implementation of a formative activity that combines the use of Lesson Study and Criteria of Didactical Suitability as a methodological tool to organize the reflection of the teacher. In the first part, it is argued that the combined use of the Lesson Study (LS) and Didactical Suitability (CDS) allows to overcome the limitations and extend the advantages of both methodologies and, in the second, we analyse the role of the Criteria of Didactical Suitability in a Lesson Study experience, before that tool has been taught to the participants in the framework of a training course that combines both methodologies. The results show that the Criteria of Didactical Suitability are present in the reflection carried out by the participants in the Lesson Study, although these criteria have not yet been taught.