<![CDATA[This study aimed to develop a case study-based basic mathematics module for science education students and to analyze its validity in supporting mathematical reasoning skills. The study employed a Research and Development (R&D) method adapted from the Borg and Gall model, which consisted of needs analysis, product design, module development, expert validation, and limited trial stages. The developed module integrated contextual science-related cases into basic mathematics learning to encourage students’ analytical and reasoning abilities. The validation process involved three experts, namely a media expert, a material/concept expert, and a learning practitioner. There are three validators, consisting of two mathematics lecturers (media experts and material/concept experts) and one science education lecturer (material/concept expert and learning practitioner). Data were collected using validation sheets and student response questionnaires. Content validity was analyzed using Aiken’s V index. The results showed that the module achieved a very high validity level, with Aiken’s V scores ranging from 0.87 to 0.92 across all assessed aspects. Revisions suggested by validators included improvements in visual presentation, contextual illustrations, and the addition of visual representations in several case activities to strengthen students’ conceptual understanding. The findings indicate that the developed module is valid for use in basic mathematics learning]]>
