<![CDATA[This study aims to determine the effectiveness of the use of Student Worksheets (LKPD) based on Problem Based Learning (PBL) in improving students' critical thinking skills in mathematics subjects in grade 5 of elementary school. The research method used is classroom action research with a pre-test and post-test design. The subjects of the study were 20 students of grade 5 of UPTD SDN 1 Metro Selatan. The research data were obtained through a critical thinking ability test carried out before (pretest) and after (posttest) the implementation of LKPD based on PBL. The results showed a significant increase in students' critical thinking skills. The average pretest score of 52.25 increased to 78.5 in the posttest, with an average increase of 26.25 points or 50.24%. Individual analysis showed that all students (100%) experienced an increase in scores from pretest to posttest. A total of 16 students (80%) managed to achieve scores above 75 in the posttest, indicating a good level of mastery of critical thinking skills. The results of this study prove that PBL-based LKPD is effective in improving students' critical thinking skills in mathematics learning. The PBL approach that presents contextual problems encourages students to think analytically, evaluatively, and creatively in solving mathematical problems. This study recommends the use of PBL-based LKPD as an alternative learning strategy to develop high-level thinking skills in elementary school students.]]>
