This study aims to analyze the increase in students' Critical Thinking Skills (CBC) through the application of the Problem Based Learning (PBL) learning model in the subjects of Natural and Social Sciences (IPAS) in grade 4 of SDN 02 Dempelan. The research design used a learning through action (CAR) approach with two cycles of planning, implementing, observing, and reflecting. The results showed an increase in student learning outcomes after applying the PBL method, with the average student score increasing from cycle 1 to cycle 2, namely 77 with a percentage of 86% in cycle 1 to 85 with a percentage of 100% in cycle 2.