The Development of Ethnomathematics-Based Teaching Materials on the Topic of Geometric Transformations

This study aims to develop a product in the form of ethnomathematics-based mathematics teaching materials on the topic of geometric transformations. This research is a development study using the ADDIE (Analysis, Design, Development, Implementation, and Evaluation) instructional design model. The product validation test was conducted by submitting the drafted teaching materials to a media expert, who was a mathematics teacher at SMP Negeri 1 Padangsidimpuan, North Sumatra, Indonesia, using a validation assessment sheet. Data were collected using a validation sheet instrument to determine the feasibility of the teaching materials, based on a specified grid, which was then analyzed to assess the validity of the developed product. The validation data were obtained from the sheets completed by the expert. The result of this research is a set of ethnomathematics-based teaching materials on geometric transformations that has been developed and validated as suitable for use in learning. The validation results from the mathematics teacher expert, covering four assessment aspects—content feasibility, presentation feasibility, language feasibility, and contextual aspects—were analyzed by considering the validator's suggestions and comments as a reference for refining the materials. The scoring categories were as follows: "1" for very poor, "2" for poor, "3" for good, and "4" for very good. The recapitulation of the validator's assessment yielded the following scores: content feasibility 82% (very valid), presentation feasibility 75% (valid), language feasibility 78% (valid), and contextual aspect 81% (very valid). The overall mean score was 79%, which falls into the valid category. Therefore, it is concluded that the developed ethnomathematics-based teaching materials on Geometric Transformations are valid and feasible for implementation.