ABSTRACT
The main purpose of this study was to develop instructional media to accompany teaching material for selected topics in plane geometry for junior high school in Bali. To do so, a development study was conducted following Plomp’s developmental model. Based on the results of needs assessment and analysis of instructional processes in the classroom, it was found that one problem for teachers is the difficulty in delivering geometry instruction. This is partly due to the unavailability of appropriate learning media. Computer—aided learning, together with dynamic mathematics software, offers a promising solution to this problem. To achieve this, a number of instructional media have been developed, based on GeoGebra. The developed media is dynamic and explorative in nature. The use of such media is expected to bring the geometry classroom to life in the sense that students can actively engage in the process of learning achievement both physically and mentally. With the aid of these media, students are able to explore geometrical objects by dragging them with a mouse, to observe what happens during this dragging process, to discuss with their counterparts, to formulate conjectures, and—facilitated by teachers—draw conclusions. This learning process is in line with the scientific approach currently being emphasized in the curriculum. In addition, these activities provide opportunities for students to develop mathematical competencies and higher-order thinking skills. In this way, the internalization of geometrical concepts occurs more constructively and, thus, persists longer in students’ cognitive constructs.
