Development and Evaluation of Design Thinking Process (DTP)-Based Instructional Materials in Trigonometry

This study developed and evaluated Design Thinking Process (DTP)-based instructional materials in Trigonometry at Paulba National High School, Schools Division Office of Ligao City, for School Year 2025–2026, and determined their effectiveness in improving students' academic performance and engagement. Grounded in the Triadic Model of DT-Enhanced Mathematical Learning—integrating Constructivism, the Cognitive Theory of Multimedia Learning (CTML), and Self-Determination Theory (SDT)—six DTP-based worksheets with accompanying lesson plans were developed, covering all Most Essential Learning Competencies (MELCs) in Grade 9 Trigonometry. Each worksheet was structured around the five iterative stages of Design Thinking (Empathize, Define, Ideate, Prototype, and Test) and contextualized using locally relevant, real-world scenarios from the community of Paulba, Ligao City. A panel of ten expert evaluators assessed validity using the DepEd LRMDS Evaluation Rating Sheets across content quality, instructional design, and technical characteristics, yielding an overall validity rating of 3.97 (Very Satisfactory). A quasi-experimental pretest–posttest design with two intact Grade 9 sections measured effectiveness; the experimental group recorded a substantially higher mean gain of 23.72 points (T=22.2 at ) compared to 14.55 points in the control group (T=11.04 at ). Student engagement—measured via a researcher-developed 5-point Likert-scale survey (Cronbach's α = 0.979)—demonstrated a higher overall mean in the experimental group (4.11 vs. 3.94), with the most pronounced gains in cognitive and self-efficacy dimensions. Although the DTP-based instructional materials revealed several limitations along implementation, need for teacher scaffolding, scope and generalizability, and resource sensitivity, these findings confirm that DTP-based instructional materials are both valid and highly effective in improving trigonometry achievement and fostering multidimensional student engagement among Grade 9 learners.