<![CDATA[This study aims to develop and examine the effectiveness of a Riau Malay ethnomathematics-based learning module integrating the Batik Nagori Kuansing motif for elementary plane geometry instruction. The study employed a Research and Development approach using the ADDIE model, consisting of analysis, design, development, implementation, and evaluation stages. The modules validity was assessed by three expert validators and achieved an Aikens V index of 0.87, indicating a high level of validity. Practicality was evaluated through teacher and student questionnaires, with results showing highly practical categories, as reflected by teacher responses of 87.84% and student responses of 91.76%. To measure effectiveness, a pretestposttest design was implemented involving an experimental group and a control group. The results revealed a statistically significant improvement in the experimental groups learning outcomes after using the ethnomathematics-based module, while no significant improvement was observed in the control group. These findings demonstrate that the ethnomathematics-based module integrating Batik Nagori Kuansing motifs is valid, practical, and effective in enhancing elementary students understanding of plane geometry. The integration of culturally meaningful motifs supports students in connecting abstract geometric concepts with real-life cultural contexts. The developed module is therefore suitable for implementation in elementary mathematics learning.]]>
