Thinking process of 7th class students in understanding quadrilateral concepts based on Van Hiele theory

This study describes the thinking process of 7th class students in understanding quadrilateral concepts based on the van hiele theory. This research is a descriptive research with qualitative approach. The research instrument used was the researcher, the latest question sheets and interviews. Data collection methods used were tested and interviews. Data analysis techniques include data reduction, data presentation, and drawing conclusions. The results showed that S1 underwent an assimilation process when determining a rectangle is a parallelogram because S1 can correctly state the reason why a rectangle is a parallelogram. This shows that S1 has met level 2 (Informal Deduction) even though S1 has not been able to prove. S2 undergoes assimilation when answering questions. S2 begins to experience disequilibrium when S2 is asked about the number of vertices as evidenced by long silences. But after being given an understanding of the concept, S2 began to understand and there was an equilibrium. Then S2 experiences, accommodation when restating the nature of the rectangular shape. This shows that S2 has met level 2 (analysis). S3 undergoes an assimilation process because S3 chooses a shape which is a rectangular shape based on S3’s knowledge. This indicates that S3 meets level 0 (Visualization).