Critical reasoning ability is a fundamental competence that needs to be developed from the elementary school level, especially in mathematics learning. This article aims to describe the implementation of the Realistic Mathematics Education (RME) approach in data processing learning, specifically bar chart material, as an effort to strengthen the critical reasoning of grade 3 students at SD Negeri 109 Pekanbaru. The research uses a qualitative descriptive approach with data sources in the form of In-Depth Learning Plans (RPM), Student Worksheets (LKPD), and assessment documents. Data collection was conducted through analysis of learning documents and observation of learning activities. The results show that the application of RME stages—contextual problem orientation, concept exploration and discovery, discussion and negotiation, formalization and generalization, and reflection and evaluation—systematically encourages students to build conceptual understanding of bar charts through real experiences. Authentic classroom data survey contexts, such as students' favorite sports and beverages data, help concretize abstract concepts so that students are able to read, analyze, and interpret information independently. Integration of Deep Learning principles (Mindful, Meaningful, Joyful) in the RPM also supports active engagement and critical reasoning of students. These findings confirm that authentic context-based RME is an effective alternative in elementary school mathematics learning aligned with the Merdeka Curriculum.
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