Development of a Geoboard Assisted Supplementary Learning Book on Triangles and Quadrilaterals to Enhance Students’ Mathematical Understanding Ability

Abstract

This study aimed to develop a geoboard-assisted supplementary book on triangles and quadrilaterals that is valid, practical, and effective in improving junior high school students’ mathematical understanding ability. The study employed a Research and Development (R&D) method using the ADDIE model, which consists of five stages: Analyze, Design, Development, Implementation, and Evaluation. The participants were 16 seventh-grade students from one Islamic junior high school (MTs) in East Lombok Regency. Data were collected through expert validation sheets, student response questionnaires, and mathematical understanding tests. The results indicated that the developed supplementary book met the criteria of being highly valid, with a validation score of 82.64% from material experts and 95.00% from media experts. The practicality test obtained an average percentage score of 85.25%, categorized as highly practical, indicating that the book was easy to use, attractive, and capable of encouraging students’ active engagement during the learning process. Furthermore, the effectiveness test using the One Sample t-test revealed that the average student learning outcome score was 87.69, which exceeded the school’s Minimum Mastery Criterion (MMC) of 70, with a significance value of 0.000 < 0.05. These findings demonstrate that the geoboard-assisted supplementary book is valid, practical, and effective for use in mathematics learning. The use of the geoboard helps students understand geometric concepts more concretely and visually through exploratory learning activities, thereby supporting the improvement of students’ mathematical understanding ability. Therefore, the developed supplementary book is feasible to be used as an alternative learning resource in junior high school mathematics instruction