The development of RBL-STEM learning materials to improve the students' combinatorial thinking skills in solving transgenic sugarcane confirmation problem using PCR technique

Combinatorial thinking skills are essential for integrating parameters such as annealing temperature, DNA template volume, and the number of cycles to optimize polymerase chain reaction (PCR) techniques. This study aims to develop research-based learning (RBL) integrated with science, technology, engineering, and mathematics (STEM) learning materials to enhance students' combinatorial thinking skills in confirming transgenic sugarcane using PCR. The development process followed the 4-D model, resulting in task plans (RTM), student worksheets (LKM), and student learning outcome tests (THBM). Validation was conducted by experts, while practicality and effectiveness were assessed through a small-scale implementation involving 25 students, utilizing pre- and post-tests, observations, and questionnaires. The learning materials were deemed valid (mean = 3.6), practical (mean = 3.8), and effective, as indicated by THBM (84%), activity scores (mean = 3.7), and positive responses (87%). Analysis of pre-test and post-test results demonstrated an increase in students' combinatorial thinking skills, with students categorized into low, medium, and high levels. The RBL-STEM learning materials effectively support the development of combinatorial thinking and problem-solving skills in molecular biotechnology. These materials present a promising approach to improving combinatorial thinking in biotechnology and can be adapted to other complex scientific topics that require analytical integration.