In the world, mathematics education is one of the fields of study that occupies an important role in creating students who think logically, rational, critical and insightful. Therefore, mathematics is indispensable everyday life and a provision in the face progress of science and technology. This study aimed to assess the effect of the learning model CORE towards mathematics learning outcomes, especially those in the cognitive aspects-this research conducted at Junior High School 34 Pekanbaru with a quasi-experimental type of research. The study design uses a nonequivalent control group design with a sample of all students in class vii-1 (control class) and class vii-2 (experiment class). Data collection techniques using test techniques, observation techniques, and documentation techniques. While the data collection instruments used were a test sheet and observation sheet. Student learning outcomes tests were analyzed using descriptive statistical data analysis and inferential statistical data analysis. Results of data analysis descriptive study gained an average of learning outcomes posttest experimental classes (VII-2) = 83.70, and grade control (VII-1) = 68.02, whereas the results of t-test analysis showed that the experimental class (VII-2) is higher than the control classes (VII-1) seen from the values that t count (3,81) ˃ t table (68,02) with significance level α = 0,05. So it was concluded that the CORE model influences mathematics learning outcomes, especially on cognitive aspects.