<![CDATA[This study aims to improve students’ learning outcomes, learning activity, and reflective thinking skills through the implementation of the Project Based Learning (PjBL) model combined with Reflective Assessment on the topic of Time Duration (Speed) in Grade VI of an elementary school. The research was motivated by the low level of students’ understanding of the speed concept and their lack of active participation in IPAS learning. The study employed a Classroom Action Research (CAR) approach, conducted in two cycles, each consisting of planning, implementation, observation, and reflection stages. The participants were 25 sixth-grade students from a public elementary school during the first semester of the 2025/2026 academic year. Data were collected using learning achievement tests, student activity observation sheets, and reflective assessment questionnaires. The data were analyzed through descriptive quantitative and qualitative techniques. The results indicated that the application of the PjBL model with reflective assessment significantly improved students’ learning outcomes in each cycle. The average learning score increased from 63.2 in the pre-cycle to 76.5 in the first cycle and 88.7 in the second cycle, while the learning mastery improved from 48% to 92%. Students’ learning activity rose from the “moderately active” to the “highly active” category. Moreover, the reflective assessment encouraged students to identify their learning difficulties, formulate improvement strategies, and understand their own thinking processes (metacognition). Therefore, the implementation of Project Based Learning (PjBL) integrated with Reflective Assessment proved effective in enhancing learning outcomes, active engagement, and reflective abilities in IPAS learning, particularly in the topic of Time Duration (Speed). This strategy is recommended for implementation within the Merdeka Curriculum to foster meaningful, contextual, and student-centered learning experiences.]]>
