<![CDATA[This study aims to develop an Ethno–Collaborative Inquiry-Based Plane Figures Module to support deep learning among elementary school students. This study employed a Research and Development (R&D) approach using the ADDIE model, which comprised five stages: Analysis, Design, Development, Implementation, and Evaluation. The analysis stage was conducted to identify learning needs, student characteristics, curriculum requirements, and the potential of local ethnomathematics relevant to plane geometry. The design stage focused on developing the module structure, learning objectives, collaborative inquiry activities, learning materials, exercises, and evaluation instruments. The development stage involved producing the initial module and conducting expert validation. The implementation stage involved 38 fifth-grade students at Khadijah Bagik Nyaka Islamic Elementary School, East Lombok, West Nusa Tenggara. The evaluation stage assessed the module’s validity, practicality, and effectiveness. The module obtained an average validity score of 90.25% and was categorized as highly valid. The practicality assessment reached 90.49%, indicating that the module was highly practical. The mean pretest score increased from 51.55 to 78.29 on the posttest, yielding an N-Gain score of 0.56, which falls in the moderate category. These findings indicate that the module successfully integrates plane geometry concepts with Sasak weaving motifs, thereby facilitating more concrete, contextual, and meaningful mathematics learning. Keywords: plane geometry module, ethno–collaborative inquiry, ethnomathematics, deep learning, elementary school.]]>
