The results showed that the implementation of the instructional
models-Open Approach in classroom teaching has resulted in the students’ development in geometric thinking from basic to analytical and from analytical to informal inference levels. Also, the way the teachers and display on the board the students’ ways of thinking and solving problems before asking them to do presentation and to explain their reasons doing so, can lead to discussion and asking questions which, in turn, allow the students an opportunity to compare and connect their thinking with their peers.