Students often find geometrical concepts abstract and difficult to understand. This results in poor performance, which contributes in the declining interest in geometry. The aim of this study was to examine the impact of using the free educational software program, "GeoGebra" on 9th grade student's mathematics achievement in learning geometry. A total of 50 students were selected from a government school located in the eastern part of India. The experimental group (25) was taught theorem on circles using GeoGebra while the control group (25) was taught utilizing traditional teaching methods. At the end of the treatment, students' mathematics achievements were measured using a post-test. The result indicated that GeoGebra is an effective tool for teaching and learning geometry in middle school.