Penelitian ini dilatarbelakangi oleh rendahnya kemampuan penalaran matematika siswa, khususnya pada siswa sekolah dasar yang disebabkan oleh pendekatan pembelajaran yang masih bersifat konvensional dan kurang bermakna. Tujuan dari penelitian ini adalah untuk mendeskripsikan perbedaan dan peningkatan kemampuan penalaran matematika siswa antara kelas yang menggunakan pendekatan Realistic Mathematics Education (RME) dan kelas yang menggunakan metode ceramah. Metode penelitian yang digunakan adalah pendekatan kuantitatif dengan jenis studi quasi ekperimen. Subjek penelitian terdiri dari siswa kelas IV SDN 1 Purwawinangun sebagai kelas eksperimen (20 siswa) dan SDN 4 Kuningan sebagai kelas kontrol (20 siswa). Teknik pengumpulan data dilakukan melalui tes uraian pretest dan posttest. Teknik analisis data menggunakan uji normalitas, homogenitas, uji-t, dan uji N-Gain. Hasil penelitian menunjukkan bahwa nilai thitung (1,925) > ttabel (1,685) pada posttest, sehingga H₁ diterima dan H₀ ditolak, yang berarti terdapat perbedaan kemampuan penalaran matematika antara kedua kelas. Selain itu, nilai N-Gain kelas eksperimen sebesar 0,77 dan kelas kontrol sebesar 0,62, menunjukkan bahwa pendekatan Realistic Mathematics Education (RME) lebih efektif dalam meningkatkan kemampuan penalaran matematika siswa.
Kata Kunci: Realistic Mathematics Education (RME), Kemampuan Penalaran, Sekolah Dasar

This study was motivated by the low level of mathematical reasoning ability among students, particularly at the elementary school level, which is largely due to the use of conventional and less meaningful teaching approaches. The purpose of this research was to describe the differences and improvements in students’ mathematical reasoning ability between a class taught using the Realistic Mathematics Education (RME) approach and a class taught using the lecture method. This study employed a quantitative approach with a quasi-experimental design. The research subjects consisted of fourth-grade students at SDN 1 Purwawinangun as the experimental class (20 students) and students at SDN 4 Kuningan as the control class (20 students). Data were collected using descriptive essay-format pretests and posttests. Data analysis techniques included normality tests, homogeneity tests, t-tests, and N-Gain analysis. The results showed that the posttest t-value (1.925) was greater than the critical t-value (1.685), indicating that H₁ was accepted and H₀ was rejected, meaning there was a significant difference in mathematical reasoning ability between the two groups. Furthermore, the N-Gain score of the experimental class was 0.77, compared to 0.62 in the control class, indicating that the RME approach was more effective in improving students’ mathematical reasoning ability.
Keywords: Realistic Mathematics Education (RME), Mathematical Reasoning Ability, Elementary Mathematics