This paper describes a Lesson Study in which in-service mathematics secondary-school teachers, collaborating with researchers, involve grade 10 students in tessellation problems. The data are collected by an experiment carried out in the context of the “Liceo Matematico” project, with three volunteer teachers. The experiment goal was to craft a collaborative design of the research lesson between teachers and researchers. The research aim of the paper is to examine the use of Lesson Study in the institutional and cultural context of Italian secondary school with the use of Cultural Transposition as a theoretical framework. The research is qualitative with idiographic aims, based on video research. The educational aim of the research is to provide a solid basis for a revamped in-service teacher education first in the context of the project, then in curricular context. Semiotic mediation is used to provide, within Lesson Study, the conceptual framework for teachers and researchers collaborative design of the research lesson. The results show that Lesson Study, as a foreign practice, is an opportunity for teachers to confront their teaching practices, to enrich their professional development, resulting in more awareness on their didactical action in and outside the classroom.

本文描述了一项课程研究，其中在职数学中学教师与研究人员合作，让 10 年级学生参与镶嵌问题。这些数据是通过在“Liceo Matematico”项目的背景下进行的一项实验收集的，该项目由三名志愿者教师参与。实验目标是在教师和研究人员之间精心设计研究课程的协作设计。本文的研究目的是以文化转换为理论框架，检验课程研究在意大利中学制度和文化背景下的应用。该研究是定性的，具有具体的目标，基于视频研究。该研究的教育目标是首先在项目背景下为改革在职教师教育提供坚实的基础，然后在课程背景下。符号调解用于在课程研究中为教师和研究人员协作设计研究课程提供概念框架。结果表明，课堂学习作为一种国外实践，是教师面对教学实践、丰富专业发展、提高课堂内外教学行为意识的机会。