The significance of teacher professional learning has been widely acknowledged in the field of teacher education, as it is often considered pivotal in bringing about changes in educational practices (Lieberman & Mace, 2008). Confronted with the need to address practical problems and encourage scientific inquiry, teacher-led research is employed in many teacher professional learning programmes (Choy & Dindyal, 2021). As an evolving research approach in education, lesson study (LS) has been increasingly popular within academia (Ding et al., 2024).

Previous research has explicated the ontology, epistemology and methodology of LS. Several studies have demonstrated its effectiveness in developing teachers’ knowledge, instructional skills and beliefs (Lewis et al., 2006; Coenders & Verhoef, 2019; Fox & Poultney, 2020). Existed empirical studies have mostly focused on cases carried out by teachers themselves. With the increasing emphasis on the cooperation between universities and primary and secondary schools, LS programmes usually involve the participation of teacher educators from universities. However, little research has investigated LS as a pathway to facilitate teacher professional learning through teacher-researcher partnership.

The objective of this empirical research is to characterise the impact of teachers’ participation in LS on the development of their professional knowledge and inquiry mindsets relevant to teaching and student learning. Specifically, this research aims to answer the following questions: (1) How do teachers’ participation in LS contribute to their professional knowledge of teaching and student learning? (2) How do teachers’ participation in LS contribute to their inquiry mindsets towards teaching and student learning? (3) What are the impacts of teacher-researcher partnership on teachers’ development in professional knowledge and inquiry mindsets?

In order to achieve the research objective, a conceptual framework is developed based on expansive learning theory, aiming to characterise participating teachers’ experiences. Expansive learning is a term raised on the basis of Vygotsky’s cultural-historical/ sociocultural theory and Engeström’s version of cultural-history activity theory, alongside many other theoretical and philosophical opinions. According to expansive learning theory, learning is interpreted as a complex activity system in which “learners are involved in constructing and implementing a radically new, wider and more complex object and concept” (Engeström & Sannino, 1999, 2017). Learners surpass the objective of directly acquiring new knowledge and skills, striving to implement what they have acquired in practice and produce something new. Such epistemology aligns with the connotation of teacher professional learning and the process of LS.

This framework interprets LS as a pathway to facilitate teacher professional learning. Teachers’ participation in LS is framed as an activity system comprising two interrelated sub-systems. The first sub-system involves a research activity system in which teachers collaborate with teacher educators to co-design classroom activities and reflect on their teaching practices. The second sub-system is a teaching activity system, which entails the application of the designed activities in actual classroom settings. Through the two sub-systems, teachers are able to generate new understandings of concepts and theories in teaching and learning, and simultaneously develop their inquiry mindsets as researchers. This framework serves as a guiding tool for data collection and facilitates the interpretation of research findings.

This ongoing study focuses on a teacher education programme involving six mathematics teachers from a secondary school in China. The programme centres around using LS to develop programming-enhanced mathematics classroom activities. Teacher professional learning is characterised through detailed analysis of multiple data sources, including conversations within the research community, observations of classrooms activities, one-on-one video-stimulated recall interviews and relevant documents. The expected findings include descriptions of the participating teachers’ development of professional knowledge and inquiry mindsets in LS, which will provide implications regarding how to effectively facilitate teacher professional learning through LS.

A qualitive case study approach is employed to uncover teachers’ experience when conducting LS and to investigate its impact on their professional learning. The selected case of this study is a teacher education programme conducted in Shenzhen, China. All six teachers participating in this programme are considered as research participants. It is a half-year programme where teachers form a DBR group to collaboratively design, implement, and reflect on programming-enhanced activities to innovate mathematics classroom teaching and learning. The research data has been collected through multiple sources before, during, and after the implementation of LS. All the programme sessions, including teachers’ research meetings and classroom teaching, have been video recorded for subsequent analysis. During planning and reflection sessions, a stationary camera has been used to capture the entire process of teachers’ conversations. During teaching sessions, a stationary camera has been used to record teachers’ teaching activities, while several hand-held cameras have been employed to record students’ learning activities. One-on-one video-stimulated recall interviews will be conducted with participating teachers at the end of this programme. Several video segments that illustrate teachers’ development in professional knowledge and inquiry mindsets will be selected as the stimulus. Teachers will be requested to watch the selected video segments and reflect on their experience of implementing LS. This is aimed at obtaining a better understanding of teachers’ perspectives regarding their participation in LS, so as further to explore the impact of LS on their professional learning. The interviews will be video recorded for analysis. Besides, relevant documents used during LS have been collected as well, including teachers’ teaching plans, student work, and other related materials. All the collected data will be systematically organised, cleaned, coded, analysed and interpreted. The video recordings will initially be verbatim transcribed and cleaned. Afterward, the data will be coded through open, focused, axial, and theoretical coding stages. This aims to integrate separated data segments into a coherent whole, which can be used to answer the research questions and reach theoretical explanations. An interpretative approach will be employed to make sense of teachers’ experience in LS. This involves the researcher making sense of teachers’ experiences, and the researcher making sense of how teachers make sense of their own experiences.

The expected findings are as follows. (1) Teachers’ professional knowledge regarding teaching and learning is developed through their participation in LS. Firstly, teachers integrate innovative techniques into classroom teaching, thereby facilitating students’ meaningful learning. This occurs during their collaborative design and implementation of classroom activities, where innovative techniques serve as a significant tool of student learning. Secondly, teachers’ content knowledge is reconstructed through the design and reflection of classroom activities within the research team. Thirdly, teachers’ knowledge of student thinking is developed by reflecting on students’ learning activities, with specific attention to their language expressions and embodied movements. Accordingly, teachers generate new understandings of instructional strategies to foster student learning, including effective responses and funds of knowledge for teaching. (2) Through LS, teachers actively engage as researchers and develop their inquiry mindsets. Their creativity and innovation are enhanced throughout this process. Teachers start by designing classroom activities based on the analysis of practical evidence and research findings, aiming to trigger innovation in teaching and learning. Subsequently, teachers collect and analyse practical data on the implementation of these activities, evaluating their feasibility and effectiveness. Based on such analysis, the activities are revised to enhance their future application. Teachers also develop a reflective stance by analysing both their teaching and research processes through several iterations. (3) LS is an iterative and two-dimensional learning process for teachers. Teachers engage in multiple cycles of design, implementation, and reflection, actively participating in two sub-systems. The first is the research activity system involving collaboration between teachers and teacher educators, and the second is the teaching activity system where teachers interact with students. Throughout this process, various influencing factors are involved, including teachers’ interaction with different stakeholders, their understanding of their roles in LS, their purposes of their involvement in LS, and their prior perceptions and experiences.

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