<![CDATA[The problem addressed in this study is the low Mathematics learning outcomes of second-grade students at SD Alam Muara Bungo, as indicated by the low level of student engagement in the learning process and the less-than-optimal achievement of learning outcomes. This study aims to improve students' Mathematics learning outcomes through the implementation of the cooperative learning model of the Student Teams Achievement Division (STAD) type. This study employed Classroom Action Research (CAR), which was conducted in two cycles, with each cycle consisting of the stages of planning, action implementation, observation, and reflection. The subjects of the study were second-grade students at SD Alam Muara Bungo, while the objects of the study were learning activities and Mathematics learning outcomes through the implementation of the STAD model. Data were collected through observations of teacher and student activities and learning outcome tests. The data were analyzed using descriptive quantitative analysis by comparing the percentages of activities and learning outcomes in each cycle. The results showed that teacher activity increased from 81.05% in Cycle I to 89.19% in Cycle II, while student activity increased from 68.12% to 87.55%. The average learning outcome score increased from 73.05 in Cycle I to 82.95 in Cycle II, with classical mastery reaching 80.00%. Therefore, the implementation of the STAD cooperative learning model can improve the Mathematics learning activities and outcomes of second-grade students at SD Alam Muara Bungo through collaborative activities, group discussions, and mutual assistance among students.]]>
