Aside from being one of the systematically arranged disciplines, mathematics is also a social construction that views humans as active subjects in building knowledge through interaction with the surrounding environment. Therefore, in addition to being a medium to enhance students’ understanding of mathematical concepts, mathematics education should also apply the principles of social activity while linking mathematical concepts to social issues. This research is intended to reform mathematics learning so that it does not merely focus on students’ understanding of mathematical concepts, but also improve their quality through the application of ‘social justice in mathematics education’, while at the same time internalising issues related to social justice through the application of ‘social justice through mathematics education’ concepts. This study used action research as the research methodology considering its actionbased themes and characteristics, where the teacher performed and simultaneously reflected learning activities. The findings obtained from this study are: (i) several challenges related to the application of ‘social justice in and through mathematics education’ in mathematics learning area, among others, include the difficulty of changing the teacher’s mindset on how to teach mathematics to students equitably (socially) and how to foster teacher sensitivity in designing mathematics learning that integrated justice issues into mathematics learning; (ii) the implementation of the principle of ‘social justice in and through mathematics education’ in order to improve the quality of mathematics learning is felt to be ineffective because of the teacher’s ability to design and implement mathematics learning involving ‘social justice in mathematics learning’ and ‘social justice through mathematics learning’ remains adequate; and (iii) the application of ‘social justice in and through mathematics education’ has a significant effect on student involvement in mathematics learning. It is characterized by more active students in learning and more enthusiastic students in learning activities, because the material that is discussed very closely with students’ daily experiences. Furthermore, the findings of this study are expected to contribute to the reform of mathematics education, especially those related to productive mathematics learning, the planting of effective mathematical concepts in students, equitable mathematics learning, and simultaneously internalizing social justice issues through the application of concepts, such as building students’ character. By using the elements in the planning and reflection of lessons, teachers are able to develop a comprehensive guide for improving the quality of their lessons and at the same time internalize students’ character building by using social justice issues
