The implementation of GeoGebra software-assited DDFC instructional model for improving students' Van-Hiele geometry thinking skll

This research aims to discover the improvement of students' Van-Hiele based on geometry thinking skills (visualization, analysis, ordering and deduction) through GeoGebra Software-assisted DDFC (Definition, Design, Formulation, and Communication) instructional model. This research employs quasi-experimental method with pretest and posttest control group design. The research was conducted in State of Junior High School (SMPN) 8 Bandung, Indonesia. The data population in the current research were grade VII students. The students of VIIF and VIIG classes were selected through random sampling. GeoGebra Software-assisted DDFC Instructional model was applied in VII F, while conventional method was employed in VIIG. Based on the analysis, it can be concluded that: 1) the students' geometrical level on each Van-Hiele's thinking skill level (visualization, analysis, ordering and deduction) in GeoGebra Software-assisted DDFC instructional model and conventional learning model is improved from pretest to posttest, 2) there is a difference on students' Van-Hiele geometry thinking skill degree of acquisition between the students who received GeoGebra software-assisted DDFC instructional model and conventional learning model, 3) thereis a difference on students' Van-Hiele geometry thinking skill achievement between the students who received GeoGebra software-assisted DDFC instructional model and conventional learning model.