AbstractThis study aims to determine the effectiveness of Circle Geometry Board (CG-Board) strategy in learning Circle Geometry towards Form Four students’ performance. This study also examined students’ Van Hiele’s level of Geometric Thought. The pre-test and post-test non-equivalent control group quasi-experimental designed was used. The selection of subjects was conducted by cluster probability sampling involving 52 Form Four students at a school in Hilir Perak district. The subjects were divided equally into control and treatment group. A three-week intervention was carried out. The instruments used are prior knowledge test, a set of pre-test and post-test on Circle Geometry and observation checklist. Descriptive analysis was used to describe students’ performance in the topic while independent t-test was used to determine the differences between the teaching strategies. The result showed that there was an increase in students’ performance in both control and treatment groups. Ba.....