Evidencing student learning in lesson and learning study: a triangulation matrix

Purpose This conceptual paper strengthens the basis on which lesson study and learning study justify claims about student learning without treating classroom data as proof. It reframes evidencing learning as a problem of proportionate warrant linking claims, the object of learning, enacted lessons, student responses and redesign. Design/methodology/approach Following Jaakkola (2020) conceptual synthesis and theory-adaptation approach, the paper integrates scholarship on lesson study, learning study, variation theory, classroom-assessment validity, argument-based validity, evidence-centred design and triangulation. The framework is illustrated through a secondary reanalysis of Runesson (2007) learning study. Findings Triangulation in lesson and learning study should be claim-centred, object-of-learning-sensitive, theory-aware and discrepancy-aware. The proposed nine-element matrix connects a learning claim with the focal critical aspect, lesson episode, direct warrant, blind spot, complementary or discrepant source, interpretation rule, rival explanation and next-cycle implication. The analysis yields more bounded claims about discernment, enacted and lived objects of learning and design implications than a loose multi-source reading. Originality/value The paper provides a field-specific evidentiary framework integrating validity argumentation, Learning Study concepts and triangulation. It offers a practical heuristic for collaborative planning, research-lesson observation, post-lesson discussion and reporting while addressing documented concerns about validation and methodological transparency.