摘要：The purpose of this research is to analyze the effect of GeoGebra in threedimensionalgeometry learning on students 'mathematical communication ability asa whole and based on students' prior mathematical abilities. This quasiexperimentalresearch with randomized posttest only design included 84 XII gradestudents in high school in Central Jakarta, Indonesia. Before the research, studentswere grouped based on their prior mathematical abilities including high, mediumand low groups. The research data were the results of mathematical communicationskills tests consisting of 7 questions which were then analyzed by Mann- Whitneytest. The results reveal that overall and for students with high and mediummathematical prior abilities, there were significant differences in mathematicalcommunication skills between students who received GeoGebra assisted Geometrylearning and students who obtained conventional mathematics learning, while forstudents with low prior mathematical ability, there is no significant difference.
