摘要：ABSTRACT This type of research is classroom action research that aims to improve students' mathematics learning activities in the subject matter of addition and subtraction using the Mastery Learning approach in Class II of SD Negeri 065853 Medan Denai. The subjects in this study were Class II students of SD Negeri 065853 Medan Denai with the number of students 32 people in the academic year 2017/2018. Data analysis techniques used by using percentage data analysis.
