<![CDATA[Measurement learning is a fundamental and applicable mathematical topic in everyday life, but it often causes learning difficulties for students, especially in understanding the meaning of units, relationships between quantities, and the conceptual measurement process. These difficulties are not only caused by students' limited cognitive abilities, but also by learning designs that do not fully facilitate social interaction and student learning development. This study aims to reconstruct the contextual didactic design in measurement learning by reviewing the role of social interaction and the Zone of Proximal Development (ZPD) in the student learning process. This study uses a qualitative approach with the type of Didactic Design Research (DDR). The research stages include analysis of the initial didactic situation to identify student learning barriers, implementation of contextual didactic design in measurement learning, and retrospective analysis of student responses as a basis for reconstructing the didactic design. Data were collected through learning observations, analysis of student work results, interviews, and learning documentation. Data analysis was carried out qualitatively by examining social interaction patterns, forms of scaffolding, and student movements in the Zone of Proximal Development. The results of this study indicate that understanding of measurement concepts develops through social interactions between students and between students and teachers within a meaningful learning context. Social interactions and scaffolding provided gradually can encourage students to move from actual abilities to potential abilities within the Zone of Proximal Development. Retrospective analysis indicates that reconstruction of the didactic design is necessary to refine the learning context, activity sequence, and scaffolding strategies to better align with students' learning characteristics. The reconstruction of the didactic design can reduce learning barriers and improve the quality of students' conceptual understanding in measurement learning. This research provides theoretical contributions to the study of social constructivism-based mathematics education and provides practical implications for teachers in designing measurement learning that is more responsive to social interactions and student learning development.]]>
