<![CDATA[This study aims to determine the implementation of learning mathematics on the subject of relationships and functions. Based on the competency-based curriculum with the CTL approach, improvements or changes that occur, various obstacles faced, and efforts that can be made to overcome these obstacles. The research was conducted through classroom action research. The approach that researchers used in this study was a quantitative approach. The approach referred to here refers more to the type of research conducted and lies in the way researchers analyse data. The research method that researchers use is quasi-experimental design. This study only involved one class that received learning treatment using the CTL approach. The population in this study was class X students of SMAN 1 Tebing Syahbandar, which consisted of 36 students. The results showed that the implementation of high school mathematics learning focused on the subject matter of relationships and functions. The CTL approach is more effective both in terms of time and achievement of student competence, meaningful, and favoured by students. Student learning outcomes in the cognitive aspect obtained an average score of 81.10, in the affective aspect with good criteria (A) about 29 students (81%) and sufficient criteria (B) there are 7 students (19%), and in the psychomotor aspect with good criteria (A) there are 34 students (93.33%) and sufficient criteria (B) there are 2 students (6.67%). In addition, there are special cognitive aspects.]]>
