Developing local instruction theory through ethnomathematics and technological-based realistic mathematics education to support students’ spatial ability

This study aims to formulate a local instruction theory (LIT) utilizing ethnomathematics and technology-based realistic mathematics education (RME) to support students’ spatial abilities. The LIT was constructed employing a design research approach, consisting of three stages: the experiment preparation, teaching experiment, and retrospective analysis. The participants were 88 junior high school students and two pre-service mathematics teachers. Data were collected through observation, interviews, and a questionnaire, which were then analyzed descriptively. The findings indicated that the LIT involved several activities. These included identifying the spatial features of Indrapatra Fort, which resembles a cylinder and a half-sphere, determining distances and cardinal directions related to these features, planning a route for a visit within the Indrapatra Fort area and writing a narrative about the visit route. Students also observed illustrations of spheres and half-spheres using GeoGebra, determined the scale for the miniature dome of Indrapatra Fort, and summarized the steps needed to create a miniature model-of the fort, which consists of a cylinder and a half-sphere. Students responded positively to the learning. Consequently, educators are encouraged to employ LIT through RME to cultivate students’ spatial ability.