This Classroom Action Research (CAR) aims to determine the increase in learning outcomes of first grade students in the mathematics content of time measurement. The research was conducted at SD Negeri Lowokwaru 02 Malang City. The research used Kurt Levin model which has 4 stages : (1) planning, including problem identification activities, problem formulation, and analysis of the causes of the problem; (2) acting, at this stage improvements are made to the problems encountered; (3) Observing, activities at this stage are data collection that is carried out by observing the extent to which the effect of the action has reached the target; (4) reflecting, the last stage in this model contains activities to review critically (reflectively) about changes that occur in (i) students, (ii) classroom atmosphere, (iii) and educators. The research subjects were all first students at SD Negeri Lowokwaru 02 Malang City, there is 28 students and domiciled in Malang City. Data sources in this study are divided into two, namely primary data sources (students) and secondary data sources (educators and documents). The results of the implementation of this research are knowing the learning outcomes of students before using the Problem Based Learning learning model in the first grade time measurement material, applying the Problem Based Learning learning model to first grade time measurement material, and improving student learning outcomes through the application of the Problem Based Learning learning model on time measurement material in first grade students SD Negeri Lowokwaru 02 Malang City