The use of technology in the pedagogical process is growing at a phenomenal rate due to the vast availability of gadgets. As a result, educationists see the urgent need for integrating technology in students' mathematical activities. Therefore, the purpose of this quasi experimental study was to investigate students' understanding in learning circles using GeoGebra. Fifty-three Year 9 (Form 3) students from two intact classes participated in this study with one class assigned as the experimental group and the other as the control. Findings of this study showed a significant difference existed in the mean scores between these two groups. The result indicated that students in the experimental group outperformed those in the control group. In addition, a survey instrument was used to elicit students' perception on the use of GeoGebra. Analysis of the questionnaire responses indicated a positive overall perception of using GeoGebra in learning about circles.