<![CDATA[Conceptual understanding is a fundamental competence in mathematics learning, yet many students still struggle to apply concepts when problems are presented in unfamiliar forms. Instruction that is centered on teachers and emphasizes procedures over meaning is often seen as a contributing factor, which calls for learning models that actively engage students in constructing knowledge. This study was motivated by the low mathematical conceptual understanding of seventh-grade Phase D students at SMP Negeri 12 Padang. The study aimed to determine the effect of the Connecting, Organizing, Reflecting, Extending (CORE) learning model on students’ mathematical conceptual understanding and to examine its improvement. A quantitative approach with a pre-experimental method and a One Group Pretest–Posttest Design was employed. The population consisted of all seventh-grade Phase D students, while class VII.8 was selected as the research sample through purposive sampling. Data were collected using a five-item essay test administered before and after the treatment. Data analysis involved the Lilliefors normality test, paired-sample t-test, gain analysis, and N-Gain analysis. The results showed that the mean pretest score increased from 44.10 to 71.58 on the posttest. The normality test indicated that the pretest and posttest data were normally distributed. The hypothesis test produced tcount = 9.18, which was greater than ttable = 2.040 at the 0.05 significance level; therefore, H0 was rejected and H1 was accepted. The mean gain was 27.471 and was classified as moderate. The gain distribution consisted of 8 students in the high category, 16 in the moderate category, and 8 in the low category. The mean N-Gain was 46.95, with 6 students in the high category, 17 in the moderate category, and 9 in the low category. These findings indicate that the CORE learning model positively influenced students’ mathematical conceptual understanding through activities that connected prior knowledge, organized ideas, reflected on understanding, and applied concepts in broader situations.]]>
