This study is stimulated by the insufficient mathematical communication skills of students and the implementation of Think-Pair-Share models in schools. This study aims to investigate whether there is a disparity in mathematical communication skills between students who take Think-Pair-Share learning and the ones who take conventional learning. This research is a quasi-experimental study. Data analysis techniques used by researchers were descriptive statistics and the Mann Whitney U test. The instrument used was a descriptive test to measure students’ mathematical communication skills. The results showed that (1) there are differences in mathematical communication skills between students using the Think-Pair-Share cooperative learning model with students using conventional learning models, (2) the student communication skills of the treated group are better than that of the untreated one. Thus, in general Think-Pair-Share learning model influences students’ mathematical communication skills.

The phenomenon that occurs in everyday life, one of the mathematical topic that was difficult to understand by students is algebraic. In algebra, there are many symbols that make students difficult to understand and understand the concept of algebraic material. This research aims to describe the ability of multi-representation in solving algebraic problems based on students’ mathematical skills (high, moderate and low). Furthermore, the type of research used was descriptive research. The subject of research in this study is class VIII students SMP Negeri 13 Singkawang, odd semester of the school year 2017/2018 Overall the research results show the multi-representation that the student presented to the verbal representation of the average percentage of 54.46%, The average visual representation of the percentage was 59.09% while for symbol representation was obtained an average percentage of 48.92%. In this case, a highly capable subject presents a solution through various representations (verbal, visual and symbol) For medium-capable subjects, it was able to give an answer with symbolic and verbal representation and lacking in visual representation presentation. As for low-capability subjects are less able to present solutions in visual, verbal and symbolic representations.