Mawardi

implement the Problem-Based Learning (PBL) model in an IPAS (Natural and Social Sciences) lesson on ecosystem harmony, aiming to enhance students' critical thinking skills. The study employed a Classroom Action Research (CAR) approach consisting of two cycles, with each cycle comprising the stages of "look," "think," and "act." Twenty-six fifth-grade students from SDN Tingkir Lor 02 Salatiga participated in the study. Students' critical thinking skills were assessed using a rubric based on the FRISCO indicators: Focus, Reason, Inference, Situation, Clarity, and Overview. The results indicate that students' critical thinking skills improved through the implementation of the PBL approach supported by the Science Escape Room medium. From an initial baseline score of 52.65%, the average critical thinking score rose to 70.94% in Cycle I and subsequently to 84.42% in Cycle II. This improvement reflects student progress in areas such as problem comprehension, reasoning, drawing conclusions, considering context, effectively communicating ideas, and reviewing their own thought processes. Thus, fifth-grade students at SDN Tingkir Lor 02 Salatiga were able to enhance their critical thinking skills while studying the IPAS topic of Ecosystem Harmony through the use of the Science Escape Room medium combined with the Problem-Based Learning model. Keywords: Problem Based Learning, Escape Room Sains, critical thinking skills, IPAS, FRISCO.