Development of a Three-Dimensional Geometry Instrument to Measure Mathematics Students’ Problem-Solving Ability

Abstract

The ability to solve three-dimensional (3D) geometry problems is an essential competence for mathematics education students, particularly because geometry requires skills in representation, reasoning, and spatial visualization. However, instruments specifically designed to measure students’ problem-solving ability in 3D geometry are still limited. This study aimed to develop a test instrument to measure the problem-solving ability of prospective mathematics teachers in solving 3D geometry problems. The developed instrument was an essay-type test based on geometric concepts, focusing on three-dimensional geometry and consisting of four items. The instrument was developed using the ADDIE R&D model (Analysis, Design, Development, Implementation, and Evaluation). The validation process included expert validation and empirical validation. The results of expert validation indicated that the instrument had high validity, as shown by a Gregory index of 1. The results of empirical validation showed that all test items were valid and reliable, with a reliability coefficient of 0.666. The validated instrument was then implemented to measure students’ problem-solving ability. The findings revealed that the average score of students’ problem-solving ability was 40 (SD = 20.37), with the highest score of 85 and the lowest score of 6 on a scale of 0–100. Therefore, it can be concluded that the developed test instrument is valid and can be used to measure students’ problem-solving ability in solving 3D geometry problems.