Kemampuan Representasi Matematis Luas dan Keliling Lingkaran Berdasarkan Teori Bruner di SMPN 9 Pontianak

This study is aimed to determine the ability and factors that caused the mathematical representation according to students' competence level in solving problems of area and perimeter of a circle. The method used was descriptive research in case study design. The subjects of research were students of grade VIIIA of SMPN 9 Pontianak. The results showed that the factors that caused low capacity of representation as follows: (1) Student who had a high competency level in enactive representation is caused by low of reasoning; the iconic representation is caused by difficulties in connection, while the symbolic representation is caused by a low conceptual understanding. (2) Student who had an intermediate competency level in enactive representation is caused by low of reasoning; the iconic representation is caused by low of reasoning, while the symbolic representation is caused by a low conceptual understanding. (3) Student who had a low competency level in enactive representation is caused by procedural disfluencies, the iconic representation is caused by the misconceptions, while the symbolic representation due to weak memory