The Non-Cumulative Dynamics of Educational Reform: Learning by Teaching as a 45-Year Case Study

This working paper examines a structural problem of educational reform: the limited cumulative integration of existing pedagogical knowledge. Using Learning by Teaching (Lernen durch Lehren, LdL), developed by Jean-Pol Martin since the early 1980s, as a 45-year longitudinal case, the paper compares recurring reform objectives such as learner autonomy, participation, cooperation, responsibility, self-directed learning and changing teacher roles with the continued existence of an operational pedagogical model addressing many of these objectives. The analysis does not claim that LdL originated these reform goals or that later approaches derived from it. Rather, it identifies a broader pattern: educational reform discourse can repeatedly formulate substantially similar objectives without systematically integrating, testing, refining and scaling already existing models. The paper proposes the concept of a deficit of cumulative knowledge organization as a complement to the well-known implementation and transfer problems of educational innovation. It further considers whether artificial intelligence may improve the memory architecture of educational knowledge by reconnecting contemporary reform questions with older theories and practices across changing terminology. Learning by Teaching is therefore used not primarily as an object of recognition, but as a longitudinal probe into the capacity of educational systems to remember, connect and cumulatively develop pedagogical innovation.