A mathematics teacher’s professional growth through multi-dimensional interactions in an interdisciplinary “time” lesson study: a reflective self-study

Purpose This reflective self-study examines how multi-dimensional interactions within an interdisciplinary lesson study on “Time” contributed to my professional growth as a novice mathematics teacher. It focuses on the interaction patterns that supported changes in my instructional beliefs, design practices, and professional understanding. Design/methodology/approach Drawing on a reflective narrative self-study embedded in iterative lesson study (LS) cycles, I documented and analyzed my experiences in a project initiated during my master's program. Data sources included iterative versions of lesson plans, classroom video recordings, reflective journals, post-lesson discussion transcripts, and student work samples. The analysis combined thematic narrative analysis and inductive coding to identify and compare recurrent “trigger–response” interaction patterns across different kinds of interactions. Cross-material triangulation was used to enhance the credibility of the findings. Findings Across two LS cycles, five recurring patterns of interaction were identified: supervisory guidance, engagement with curricular texts, cross-disciplinary collaboration in co-constructing integrated lesson designs, responsive exchanges with students, and systematic self-reflection. These patterns appeared in my design, enactment, and assessment decisions. Together, they marked a shift in my professional role – from implementing isolated subject-based lessons to designing interconnected learning experiences – and repositioned my instructional stance from delivering content to facilitating disciplinary understanding through interdisciplinary inquiry. Originality/value This study offers a first-person, longitudinal account of professional growth in a Chinese elementary mathematics context. It shows how intentionally structured, multi-dimensional interactions within lesson study can accelerate teachers' development, particularly under the current policy demands for interdisciplinary thematic learning.