Kemampuan berpikir kritis matematis (KBKM) merupakan kemampuan yang sangat dibutuhkan dan penting dalam pembelajaran Matematika. Sejumlah penelitian menyatakan bahwa Realistic Mathematics Education (RME) efektif dalam meningkatkan kemampuan matematis, termasuk KBKM. Penelitian tersebut umumnya menggunakan pendekatan kuantitatif, sementara di sisi lain pendekatan mixed-methods untuk mengeksplorasi dan memahami efektivitas RME terhadap KBKM masih langka. Untuk mengisi kesenjangan tersebut, penting dilakukan penelitian dengan mempertimbangkan desain penelitian yang mengumpulkan dan menganalisis data kuantitatif dan kualitatif sekaligus. Penelitian ini bertujuan untuk mengetahui efektivitas RME terhadap KBKM siswa yang dibelajarkan dengan RME dengan cara membandingkan pretest dan posttest siswa yang dibelajarkan dengan RME dengan pembelajaran konvensional, dan untuk memahami persepsi siswa terhadap efektivitas RME. Pengumpulan data pada studi embedded-experimental mixed methods mengumpulkan data kuantitatif melalui tes, sementara data kualitatif melalui wawancara bersama siswa kelompok eksperimen. Hasil analisis terhadap data kuantitatif menggunakan independent sample t-test dan uji n-gain score menunjukkan bahwa RME lebih efektif meningkatkan KBKM dibandingkan pembelajaran konvensional. Hasil analisis kualitatif sejalan dengan hasil analisis kuantitatif tersebut, menunjukkan bahwa RME dapat meningkatkan KBKM siswa. Selain itu, hasil analisis kualitatif menghasilkan tema utama, yaitu: persepsi siswa terhadap matematika dan pembelajarannya, kesan terhadap RME, peningkatan KBKM, keterlibatan siswa pada pembelajaran, persepsi terhadap masalah realistik, dan kesulitan selama implementasi RME.

Kata Kunci: Berpikir Kritis Matematis, Realistic Mathematics Education, Mixed-Methods, Aritmetika Sosial, Matematika Sekolah

Mathematical critical thinking ability (MCTA) is an ability that is needed and important in learning mathematics. Numerous studies have demonstrated the effectiveness of Realistic Mathematics Education (RME) in enhancing various mathematical abilities, including critical thinking. However, most of these studies employed a quantitative approach, while on the other hand, a mixed-methods approach to explore and understand the effectiveness of RME on MCTA was still rare. To address this gap, it was important to conduct research that simultaneously collected and analyzed both quantitative and qualitative data. This study aimed to determine the effectiveness of RME on students' MCTA by comparing pretest and posttest results of students taught using RME versus conventional learning, and to understand students' perceptions of RME's effectiveness. The research employed an embedded-experimental mixed methods design, gathering quantitative data through tests and qualitative data through interviews with students in the experimental group. The results of the quantitative data analysis using independent sample t-test and n-gain score test indicated that RME was more effective in improving students' MCTA compared to conventional learning. The qualitative data analysis supported these findings, revealing that RME significantly enhanced students' MCTA. Furthermore, the qualitative analysis identified several main themes, namely: students' perceptions of mathematics and its learning, their impressions of RME, the improvement of MCTA, student involvement in learning, perceptions of realistic problems, and difficulties encountered during the implementation of RME. Keywords: Mathematical Critical Thinking, Realistic Mathematics Education, Mixed-Methods, Social Arithmetic, School Mathematics