<![CDATA[This research is based on the facts that students often made mathematical errors when dealing with mathematical problems. It was implemented in class VII-4 which consists of 28 students with diverse background, academic abilities, interests, and learning style. Data was obtained through observations and interviews with mentor which showed need for reducing students’ mathematical errors. The Missouri Mathematics Project (MMP) strategy was implemented to reduce students’ mathematical errors through cooperative and individual works steps. The methods that are used in this study is descriptive research with qualitative approach to describe mathematical errors and it is combined with Kastolan theory as the way to analyze those errors. The analysis process used students’ results in formative and summative assessments as supporting data in describing students’ mathematical errors. The results of individual formative and summative assessments showed a substantial reduction in the rate of mathematical errors among students. On the other hand, students who initially did not achieve the Minimum Passing Score (MPS) on the formative assessment may achieve the MPS on the summative assessment. The implementation of MMP strategy showed improvement in terms of (1) students’ understanding about the material, (2) ability to work together, (3) ability to work individually, (4) reducing of students’ mathematical errors. Through this process, teacher realize the importance of systematic and holistic learning design so that it not only increases academic abilities but also forms a good character. As a follow-up, it is recommended to use MMP strategy integrated with technologies to further minimize students’ mathematical errors.]]>
