摘要：AbstractGeometry is a basic skill to be mastered. It is important in architecture and design, in engineering and in various aspects of construction work. However, in Malaysian education system, the process of teaching and learning geometry does not reflect its importance. The process does not emphasise the thinking skills, whereas the mathematics syllabus clearly states that thinking systematically, accurately, thoroughly, diligently and with confidence, should be infused throughout the teaching and learning process. Therefore, the aim of this study was to test the effectiveness of Van Hiele's phases of learning geometry using the Geometer's Sketchpad (GSP) on students’ degree of acquisition of Van Hiele levels. This quasi-experiment involved two groups of students; treatment and control group. The students in treatment group learned Form Two's Transformation topics through the Van Hiele's phases of learning using the GSP, while the students in control group learned the same topic conventionally. Before the study started, five students from each group were randomly selected to be interviewed to determine their initial levels of geometric thinking. The experiment took place for six weeks. At the end of the study, the same students in both groups who had been selected earlier were interviewed for the second round to analyse their final levels of geometric thinking. The results found that in their initial levels of geometric thinking, the majority of students in both groups obtained the first Van Hiele levels with complete acquisition. However, almost all students in both groups showed a low acquisition of level 2 and no acquisition of level 3. In the post interview, most of the students in control group showed an increment of geometric thinking that is from level 1 to level 2, but no one in this group achieved level 3. In contrast, all students in the treatment group showed a complete acquisition of Van Hiele level 1 and almost all of them indicated a complete acquistion of level 2. As for level 3, only one student did not achieve that level, whereas the rest showed a complete and high level of acquisition. Therefore, it can be concluded that the implementation of activities based on the Van Hiele phases of learning geometry have a positive impact on the development of higher levels of geometric thinking.
关键词：geometry;Geometer's Sketchpad (GSP);geometric thinking;degree of acquisition of Van Hiele levels
