This study aims to develop digital teaching materials based on ethnomathematics to enhance the geometry problem-solving abilities of eighth-grade students at SMP Negeri 1 Kota Bima. Using the Research and Development (R&D) 4D model by Thiagarajan, Semmel, and Semmel 1974, this study underwent four stages: Define, Design, Development, and Disseminate. In the Define stage, the analysis identified that 50% of students faced difficulties in geometry. The Design stage resulted in a prototype e-module that integrates the local culture of Bima. During the Development stage, the teaching materials were validated, showing that the Lesson Plans (RPP) and Student Worksheets (LKS) required revisions, while the Syllabus was deemed excellent. The trials indicated a significant improvement in students' problem-solving abilities and a positive response to the cultural relevance in the teaching materials. The results of this study support the effectiveness of digital teaching materials based on ethnomathematics and recommend their broader application in the context of mathematics education.

Index Terms- Digital Teaching Materials; Ethnomathematics; Geometry; Problem solving skill; 4D Models.