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H. Gülbağcı1, S. Olkun2

1Marmara University (TURKEY)
2Ankara University (TURKEY)
The aim of this study was to investigate the effects of dynamic geometry activities on 7th grade students’ understanding of quadrilaterals that include the properties of quadrilaterals and the relationship between quadrilaterals.
The study was carried out at two elementary school sites in Turkey at the second term of the 2008-2009 academic year for six weeks. There were 44 7th grade students in the experimental study. A geometry achievement test prepared by the researcher was given to each group as the pre and post tests. There were 26 questions in the test. Nine of the questions were at informal deduction level of the Van Hiele geometrical thinking levels. The quadrilaterals activities were done with Geometer’s Sketchpad software in the experimental group. On the other hand, the paper and pencil activities that include the same topics were used with the control group by the same teacher. After a six week implementation of the activities, a post test was given to both groups of students. The data from geometry achievement test, activities, classroom observations and interviews were analyzed.
According to the post test results, a significant difference was found between experimental group and control group [t(42)=2,028, p< .05] . Considering nine questions of the test, there is also a significant difference between experimental group’s pre-test and post-test scores [t(40)=-5,332, p< .05]. During the activities the students were asked to define a quadrilateral however their definitions seemed to be as descriptions rather than as definitions. In the interview that was after the implementation, the researcher asked to students to classify quadrilaterals hierarchically but none of them could be able to do this task.
Consequently, the lessons throughout the dynamic geometry software are found to be more effective in the teaching of quadrilateral subject. Although not intended at the beginning, the students’ Van Hiele geometrical thinking levels also improved. Besides, 7th grade students understand the relationship between two quadrilaterals but they do not organize the hierarchical classification of quadrilaterals.