The purpose of this study was to find out how to improve mathematics learning achievement in data processing materials by applying the game method for sixth grade students in the first semester of SDN Penangsak, East Praya Subdistrict, for the 2020/2021 academic year. This research is classroom action research (CAR), so the procedure used in this research develops as usual in CAR, consisting of two cycles with the stages of activities taken in each cycle including four activities, namely (1) Planning stage (paln), (2) the stage of implementation or action (action), (3) the stage of observation (Observation), (4) stage of reflection (Reflective). The results obtained are: in the initial observations obtained information that students' learning activities and achievement in mathematics are still low, most students have difficulty understanding the material Collecting and reading data is evident from 17 students only 6 of 17 people or 35.29% who meet the standard of completeness In the first cycle obtained data on students' mathematics learning achievement with the average grade and percentage of the number of students who reached the standard of learning completeness as in table 4.2, namely an increase in student learning achievement where students who completed learning from 6 people in the pre-cycle became 12 people out of 17 people. students. In the second cycle, data on students' mathematics learning achievement was obtained with the average grade and percentage of the number of students who achieved the standard of mastery learning or there was an increase in student learning achievement from cycle I to cycle II where students who completed learning in cycle I were 11 people to 16 people. of 17 students or 94.12%