<![CDATA[Critical thinking is one of the essential 21st-century competencies that students need to address complex problems, including environmental pollution. However, the Programme for International Student Assessment (PISA) indicates that Indonesian students' critical thinking skills remain relatively low. This study aimed to develop a STEAM-based electronic student worksheet (E-LKPD) on the topic of environmental pollution that is valid, practical, and effective in fostering the critical thinking skills of tenth-grade senior high school students. The study employed the 4D development model, consisting of the define, design, develop, and disseminate stages. A limited trial was conducted with 20 tenth-grade students at SMAS Kartika IV-3 Surabaya. The research instruments included validation sheets, learning implementation observation sheets, student response questionnaires, and critical thinking skill tests. Data were analyzed using descriptive quantitative methods. The results showed that the developed E-LKPD achieved a validity score of 91.25%, categorized as highly valid. Its practicality was demonstrated by student activity implementation of 98.66% and student responses of 98.33%, both categorized as highly practical. Its effectiveness was indicated by the improvement in students' average scores from 50.65 on the pretest to 89.75 on the posttest, with an N-Gain score of 0.77 (high category). Furthermore, the average achievement of critical thinking indicators increased from 0.50 to 0.89, categorized as very good. Therefore, the STEAM-based E-LKPD is considered valid, practical, and effective in fostering the critical thinking skills of tenth-grade senior high school students.]]>
