<![CDATA[Mathematics learning in elementary schools is still dominated by conventional methods that do not foster the development of critical thinking skills. This challenge is relevant to 21st-century learning and the Independent Curriculum, which demands the integration of technology and high-level thinking skills. This research aims to analyze the effect of Brain-Based Learning (BBL) supported by PhET Simulations on the critical thinking abilities of fifth-grade students in Magelang City. The research approach uses a quasi-experimental design with a nonequivalent control group. The research instrument is an essay test to measure critical thinking abilities. The results of the analysis show that the BBL model assisted by PhET Simulation provides a significant improvement in critical thinking abilities. Data testing uses the t-test and N-Gain to prove the hypothesis. The t-test produces a significance value of 0.00 < 0.05, indicating a significant effect of using BBL assisted by the PhET Simulation. This finding is strengthened by the average N-Gain value of 0.5002, which falls within the medium category, indicating that brain-based work learning is quite effective in improving students' critical thinking abilities. Integration of BBL and PhET Simulations proved effective in supporting 21st-century skills. Implementing this model can provide learning experiences that support optimal brain function through technology, making it relevant for developing 21st-century skills.]]>
