<![CDATA[This study was motivated by the suboptimal use of digital teaching materials that support students' critical thinking skills and biology concept understanding in learning the human circulatory system. Learning activities that are still dominated by printed textbooks have limited students' opportunities to connect biological concepts with contextual problems. Therefore, it is necessary to develop teaching materials that facilitate students in learning independently, actively, and through a problem-centered approach. This study aimed to develop a Problem-Based Learning-based E-Module that is valid, practical, and effective in improving the critical thinking skills and biology concept understanding of eleventh-grade senior high school students. This study employed a Research and Development (R&D) method using the ADDIE model, which consists of five stages: analysis, design, development, implementation, and evaluation.. The validity of the E-Module was assessed by four subject-matter experts, consisting of two Biology lecturers from the Faculty of Mathematics and Natural Sciences, Universitas Negeri Padang, and two Biology teachers from SMAN 10 Padang, as well as one language expert from the Faculty of Languages and Arts, Universitas Negeri Padang. The practicality of the product was evaluated by two Biology teachers, eight students in the limited trial, and forty students in the field trial. Data were collected using validation sheets, practicality questionnaires, and tests of critical thinking skills and biology concept understanding. Validity and practicality data were analyzed using percentages, while effectiveness was analyzed using the N-Gain test, normality test, homogeneity test, and Independent Sample t-test. This study was motivated by the limited use of digital teaching materials designed to strengthen students’ critical thinking and biological concept understanding in the human circulatory system. Learning dominated by printed textbooks restricts opportunities to connect biological concepts with contextual problems and engage in independent, active, problem-centered learning. This study aimed to develop a Problem-Based Learning-based E-Module that is valid, practical, and effective for eleventh-grade senior high school students. The study employed Research and Development using the ADDIE model, comprising analysis, design, development, implementation, and evaluation. Product validity was assessed by four subject-matter experts—two Biology lecturers from Universitas Negeri Padang and two Biology teachers from SMAN 10 Padang—and one language expert from Universitas Negeri Padang. Practicality was evaluated by two Biology teachers, eight students in a limited trial, and forty students in a field trial. Data were collected through validation sheets, practicality questionnaires, and tests measuring critical thinking and biological concept understanding. Validity and practicality data were analyzed using percentages, whereas effectiveness was examined using N-Gain, normality, homogeneity, and independent-samples t-tests. The E-Module achieved a validity score of 94.91%, indicating very high validity. Teacher practicality reached 97.50%, while limited- and field-trial scores were 94.68% and 94.18%, respectively, indicating very high practicality. Critical thinking N-Gain scores were 74.47 in the experimental class and 69.91 in the control class. Biological concept understanding scores were 73.60 and 65.07, respectively. The hypothesis test yielded p < 0.001. These findings demonstrate that the developed E-Module is valid, practical, and effective in improving students’ critical thinking skills and biological concept understanding. The module therefore provides an accessible digital resource for implementing contextual PBL and supporting meaningful, student-centered biology learning in senior high school classrooms more consistently.]]>
