This research aims to develop a teaching module using a probing-prompting learning model based on ethnomathematics on the topic of flat-sided solid geometry to improve the mathematical communication ability of junior high school (SMP) students, ensuring it is valid, practical, and effective. The study employed the 4D development model (Define, Design, Develop, Disseminate), followed by a quasi-experimental study using a non-equivalent control group design. The subjects of this research were ninth-grade students at SMP Negeri 1 Sukosari, Bondowoso. The module validation results showed a very valid criterion with an average validity percentage of 92.5%7. The practicality test results obtained a value of 91.3% in the very practical category. The effectiveness test showed a significant difference in mathematical communication ability between the experimental and control classes with a significant (p < 0,05) value. Thus, the teaching module using probing-prompting based on ethnomathematics can be used to improve the mathematical communication ability of junior high school students because it is valid, practical, and effective10. Based on these results, teachers are expected to implement the probing prompting learning module by creating question guides that can enhance students’ mathematical communication ability and can be adapted to local cultural contexts as an alternative teaching material.