<![CDATA[Mathematical reasoning is an essential cognitive skill that supports students' ability to solve complex problems. This study aims to explore the mathematical reasoning of junior high school students in solving start-unknown problems in the context of geometry. A qualitative case study approach was used, with two students selected as subjects from 62 respondents based on purposive sampling techniques. Data collection was conducted through mathematical reasoning tests and semi-structured interviews. Data were analyzed using the Miles and Huberman model, while validity was tested through source triangulation. The results showed that subjects in the prima category were able to meet all reasoning indicators comprehensively, supported by good conceptual understanding and metacognitive reflection. Conversely, subjects in the prima-partial category tended to solve problems procedurally without a deep understanding of geometric representations. These findings emphasize the importance of applying backward reasoning strategies and multiple-answer approaches in geometry learning to develop higher-level mathematical reasoning. The implications of this study point to the design of more adaptive learning and encourage the need for longitudinal studies to observe students' reasoning development continuously.]]>
Copyrights © 2026
