Abstract
This study aimed to develop and preliminarily evaluate Project-Based Learning (PjBL)-based teaching materials for the Animal Development course in terms of validity, practicality, learning outcomes, critical-thinking performance, and student attitudes. A research and development approach was employed using the 4D model, consisting of Define, Design, Develop, and Disseminate stages. The developed materials were evaluated by three experts in content, media, and language aspects. Practicality testing involved lecturer responses and a limited trial with six Biology Education students, while field implementation involved 28 students at Universitas PGRI Silampari. Data were collected through expert validation sheets, response questionnaires, achievement tests, critical-thinking performance assessments, and attitude questionnaires. Data analysis was conducted descriptively using percentage scores, mean comparisons, and normalized gain analysis. The results showed that the teaching materials achieved a validity score of 92.71%, indicating a highly valid category. The practicality evaluation obtained an overall score of 87.50%, categorized as highly practical. Students’ mean achievement increased from 62.43 in the pretest to 81.25 in the posttest, with a normalized gain score of 0.50. Critical-thinking performance reached an average score of 85.50, while student attitudes toward the learning implementation obtained an average score of 85.50. These findings indicate that the developed PjBL-based teaching materials are feasible and demonstrate promising potential for supporting active, contextual, and reflective learning in biology education. The study implies that integrating project-oriented activities into discipline-specific teaching materials can provide a meaningful framework for fostering students’ scientific reasoning and critical-thinking performance.