<![CDATA[This study was motivated by the low level of mathematical concept understanding among fifth-grade students at SDN 3 Banyuputih, where many students perceived mathematics as a daunting and tedious subject due to conventional teaching methods that lacked interactive media. The study aimed to examine the effectiveness of implementing the Contextual Teaching and Learning (CTL) model, supported by BUKAR (Augmented Reality Smart Book) media, in enhancing students' understanding of mathematical concepts. A quantitative experimental method was employed—specifically, a pre-experimental design using the One-Group Pretest-Posttest format. The research sample comprised all 28 fifth-grade students at SDN 3 Banyuputih, selected via a saturated sampling technique. Data were collected through written essay tests and analyzed using a paired-sample t-test and N-Gain calculations. The results demonstrated a significant improvement in mathematical concept understanding, evidenced by the rise in the mean score from 55.1 on the pretest to 85 on the posttest. The paired-sample t-test yielded a significance value of 0.001 (< 0.05), indicating a statistically significant difference following the intervention. Furthermore, the N-Gain analysis result of 65.95% classified the model as having moderate effectiveness. The study concludes that the implementation of the Contextual Teaching and Learning model, supported by BUKAR media, is moderately effective in improving elementary students' understanding of mathematical concepts and is capable of transforming abstract material into concrete, engaging visualizations.]]>
