Özet:
This study was conducted to determine whether there are differences in van Hiele geometric thinking levels of students and to investigate whether there is a correlation between geometry academic achievement and van Hiele Geometry Test scores of students at different grade levels. The van Hiele Geometry Test was examined on the basis of Turkish geometry curricula and contents of the curricula were examined on the basis of van Hiele geometric thinking levels in order to see whether they are aligned to geometric thinking levels of the students. The study was conducted at one of the private schools in Istanbul. The students were at 7th, 8th, 10th and 11th grades. 10th and 11th grades were either at science high school or Anatolian high school. University students were at SCED and PRED departments at Boğaziçi University. The van Hiele geometric thinking levels and scores of the students were determined by the van Hiele Geometry Test which was developed by Usiskin (1982) and has been used widely in educational research studies. The Turkish version which was translated by Duatepe (2000) was administered in the study. The design of the study was causal comparative research design. The data were analyzed by SPSS 17.0. Comparison of van Hiele Geometry Test scores was carried out by ANOVA Dunnet-C Test and the correlation analyses were done by Pearson-r. Multiple comparison analyses revealed that there are significant differences between the van Hiele Geometry Test scores of students at various grade levels. Results of the correlation analyses showed that there are significant correlations between the van Hiele Geometry Test scores and geometry achievement scores of the students at 7th, 8th, 10th and 11th grade levels. The results of the study showed that the geometric thinking levels of the students may not necessarily depend on the age or maturation but may depend more on the geometry curriculum and the geometric thinking levels are correlated with the geometry achievement levels of students.
