Özet:
The purpose of this study was to investigate the effect of instruction type (origamibased and traditional instruction) on tenth-grade students‟ spatial visualization, geometry achievement and geometric reasoning concerning certain key topics in triangles. The study was conducted in a public high school in Tekirdağ with 184 tenth-grade students by using a quasi-experimental pretest-posttest design. One group (n = 94) received traditional instruction while the other group (n = 90) received origami-based instruction. In the origami-based instruction, there were twelve class hours in total. The origami-based instructional materials were designed by the researcher based on the literature. The van Hiele Test (vHT) was used to compare group differences in terms of geometric reasoning just prior to the treatment. The van Hiele Test results indicated that students in experimental and control groups had similar van Hiele levels, thereby similar geometric thinking levels before treatment. The Card Rotation Test (CRT), Cube Comparison Test (CCT) and Paper Folding Test (PFT) were used to measure students‟ spatial visualization ability. Furthermore, Geometry Achievement Test (GAT) and Geometric Reasoning Test (GRT) were developed by the researcher to evaluate students‟ geometry achievement and geometric reasoning ability, respectively. A Repeated Measures Analysis of Variance (ANOVA) was used to analyze data collected from each pretest and posttest. The results of the study revealed that there was a statistically significant change in spatial visualization, geometry achievement and geometric reasoning abilities of students who received origamibased instruction across two time periods (from pre-treatment to post-treatment). The results of this study suggested that origami-based geometry instruction could be effective to enhance students‟ spatial visualization, geometry achievement and geometric reasoning abilities.
