Development of STEM-Based Instructional Materials on Two-Variable Linear Inequalities to Enhance Students Mathematical Competence

This study aimed to develop STEM-based learning devices on two-variable linear inequalities to improve the mathematical abilities of vocational high school students. The research employed the Research and Development (R and D) method using the 4D model proposed by Sivasailam Thiagarajan. The stages included Define, Design, Develop, and Disseminate. The subjects were 26 eleventh-grade students majoring in Digital Business. The developed products consisted of teaching modules, student worksheets (LKPD), and assessment instruments. The validation result showed an average score of 3.25 (valid category). The practicality test indicated a 97% positive response (very practical), while the effectiveness test showed 80% classical mastery (≥ KKM 75). Therefore, the developed STEM-based learning devices are valid, practical, and effective for improving students’ mathematical abilities.