In the study, pre-tests and post-tests were given to the participants before and after the instruction as an independent variable. The study was conducted with pre and posttest control group quasi- experimental method. Because “it provides the best approach to investigating cause and effect relationships” (McMillan, 2000, p.
207). During the study the experimental group received computer- assisted instruction with the dynamic geometry software GeoGebra as a supplementary teaching tool, and the control group received instruction by means of traditional teaching. Accordingly,