<![CDATA[This research was motivated by teachers' difficulties in learning mathematics. The lack of teacher ability in designing and implementing methods is an obstacle to student success in mathematics subjects. This research was conducted to improve teacher performance in managing mathematics learning using the Cooperative Learning Method. The purpose of this research is to determine: 1) Student learning outcomes in solving problems regarding the area of a plane area before using the Cooperative Learning method, 2) Student activities during the learning process in mathematics learning by applying the Cooperative Learning method. , 3) Student learning outcomes in solving questions on the area of flat built areas after using the Cooperative Learning method. The method used is classroom action research (Classroom Action Research), the research process is carried out in two cycles, the previous action being carried out in the pre-cycle stage, each cycle consists of 4 stages, namely: 1) planning, 2) implementation, 3) observation, 4) reflection . The results of the research show an increase, seen from students' answers on student worksheets and an increase in students' activeness in working in groups, asking questions in class, thinking more critically and actively. Likewise, the learning results for each cycle show an increase, the average test score in the first cycle is 70.32 and the average test score in the second cycle is 86.45, while in the pre-cycle stage the average score is 54.19. Based on the research results, it can be concluded that the use of the Cooperative Learning method in mathematics learning in elementary schools can improve mathematics learning outcomes and teachers can try to apply this method so that students are active and motivated in learning mathematics.]]>
