<![CDATA[This study was motivated by students’ low mathematical reasoning ability and the limited integration of local culture into mathematics instruction. The study aimed to analyze the application of ethnomathematics through the Bendrong Lesung Dance in teaching number patterns, the improvement of students’ mathematical reasoning ability, students’ mathematical reasoning ability after instruction, and students’ responses to the learning process. This study employed a mixed-methods approach with a sequential explanatory design involving 30 eighth-grade students at SMPN 3 Cilegon. The quantitative phase used a one-group pretest-posttest design. Data were collected through a mathematical reasoning test and interviews. Quantitative data were analyzed using the Wilcoxon Signed-Rank Test and N-Gain, while qualitative data were analyzed through data reduction, data presentation, and concluding. The results of the study indicate that ethnomathematics was implemented by relating the rhythmic patterns of the pestle and mortar, as well as the dancers’ formations in the Bendrong Lesung dance, to the concept of number patterns through the Think-Pair-Share model. Students’ mathematical reasoning skills improved, as evidenced by an increase in the average score from 8.43 on the pretest to 15.03 on the posttest, with an N-Gain score of 0.5749, which is categorized as moderate. The Wilcoxon test showed a significance value of 0.000 < 0.05, indicating a significant difference in students’ mathematical reasoning skills before and after the instruction. After the instruction, students were able to make conjectures, perform mathematical manipulations, provide reasons for the solutions they found, and draw conclusions. Interview results also revealed positive feedback from students, as the instruction helped them understand number patterns more easily, made learning more engaging, and provided an opportunity to explore local culture. Therefore, ethnomathematics through the Bendrong Lesung dance can serve as an alternative approach to teaching number patterns that supports students’ mathematical reasoning skills.]]>
