Mathematical communication of junior high student based on the conceptual understanding of triangle

As we know that the mathematical communication is an important skill. Optimalization mathematical communication research gave so many option as the effort to optimalized it, such as reading, discussing, writing. All of the option was concerned about learning model and how to learn. Based on the study of literature, at least there were four aspects that could affect the mathematical communication, those were teacher, learning, the learning materials, and the student itself. Not only that four, but also conceptual understanding could affect mathematical communication because the thing that student communicate were the concept that they had. Some of problem about conceptual understanding were found in triangle. On this research, researcher use qualitative method with observation, interview and test as instrument. There were found that learning model was not the only problem of the way to optimalized student mathematical communication because mathematical communication skill not only about how teacher taught in the classroom. That's why the way to optimalized it has to be fitted to the problem that founded.