Sustainable lesson study in Italian secondary education: insights from a lesson on the regression line

Purpose The purpose of this paper is to present the adapted model of lesson study implemented in an Italian upper secondary school and sustained over the past seven years. To illustrate and reflect on this approach, the paper reports an example of lesson study activity carried out during the last school year, aimed at introducing statistical models and helping students develop a meaningful understanding of the regression line. Design/methodology/approach The study is based on the description and qualitative analysis of a lesson study utilizing an iterative cycle of four successive lessons performed in four different grade 11 classes of a scientific secondary school. The systematic process of reflection and adjustment between each session serves as a powerful model, allowing teachers to track student misconceptions and difficulties. Findings The analysis underscores the value of collaborative lesson design, observation and reflection in strengthening teachers' awareness of students' thinking processes and building a professional learning community within the school. Practical implications The paper offers practical implications for mathematics educators by demonstrating how iterative reflection can bridge the gap between instructional design and student cognition. The emphasis on strengthening the link between teaching action and actual learning provides a framework for practitioners looking to move beyond formulaic instruction toward more meaningful, student-centered statistical modeling. Originality/value Overall, the study highlights the potential of lesson study as a sustainable and adaptable practice in the Italian secondary education context. It also underscores its potential to enhance teachers' awareness and confidence in promote exploratory and meaningful activities on topics often undervalued but increasingly important in today's technological scenario, such as statistics.