Development of STEM-PjBL Digital Learning Material Integrated with Mandailing Ethnoscience for Developing Students’ Critical Thinking Skills

Chemistry learning requires learning materials that connect chemical concepts with authentic contexts while developing students’ higher-order thinking skills. This study aimed to develop digital learning material based on Science, Technology, Engineering, and Mathematics–Project-Based Learning (STEM-PjBL) integrated with Mandailing ethnoscience for acid–base solution learning and to determine its validity, practicality, and potential to support students’ critical thinking skills. The study employed a Research and Development (R&D) design using the ADDIE model. The product was validated by three material experts and three media experts and tested with two lecturers and 30 Grade XI students at SMA Negeri 5 Medan using a one-group pretest–posttest design. Data were collected through validation sheets, practicality questionnaires, and critical-thinking tests. The results showed an overall validity of 98.58% and practicality of 98.91%. Students’ critical-thinking scores increased from 32 to 88, with an N-gain of 0.82, categorized as high. Analysis and inference showed the highest N-gain (1.00), while interpretation showed the lowest (0.67). The findings indicate that the developed digital learning material is highly feasible and practical and shows potential to support critical-thinking development. However, the observed gain cannot be interpreted as causal evidence because no comparison group was included.