eng Science and Education Publishing American Journal of Educational Research 2327-6150 2018-11-23 6 11 1539 1545 10.12691/education-6-11-12 EDUCATION201861112 article Muhammad Febri Rafli febrirafli@email.com 1 Edi Syahputra 1 Yusnadi 1 Departement of Basic Education, Postgraduate School, State University of Medan, Indonesia This study aims to determine: (1) the effect of problem based learning model on students mathematical communication skills, (2) the effect of problem based learning model on students self-confidence, (3) the interaction between learning models (problem based learning and conventional learning) and early mathematics ability to students mathematical communication skills, and (4) the interaction between learning models (problem based learning and conventional learning) and early mathematics ability to student's self-confidence. This study is a quasi-experimental research. The population in this study were all students of class VIII junior high school 2 Tanjung Pura consisting of six classes. Samples were selected by simple random sampling as much as two classes. The selected class is VIII-2 as the experimental class (31 students) and VIII-1 as the control class (32 students). The instruments used are mathematical communication skills test, early mathematics ability test, self-confidence questionnaire. Data obtained from the research instruments were analyzed using two-way ANOVA by SPSS program. The results showed that: (1) there is significant effect of problem based learning model to students mathematical communication skill, (2) there is a significant effect of problem based learning model to students self-confidence, (3) there is interaction between learning models (problem based learning and conventional learning) and early mathematics ability to students' mathematical communication skills, (4) there is interaction between learning models (problem based learning and conventional learning) and early mathematics ability to student's self-confidence. http://pubs.sciepub.com/education/6/11/12/education-6-11-12.pdf problem based learning mathematical communication ability self-confidence early mathematics ability