This research was motivated by the difficulties of teachers in implementing the 2013 curriculum, especially in the preparation of learning tools. This research was aimed to develop a valid, practical and effective learning tool for VIII grade junior high school students. This type of research was Research and Development with a 4-D model. Data collection instruments in this study were validation sheets, practicality sheets and tests of mathematical communication skills. Data were analyzed using validation criteria, practicality and effectiveness tests. The results obtained from the device validation show that the RPP is valid and the LKPD is quite valid. The practicality test results of small groups and large groups obtained very practical criteria. The effectiveness test can be seen from the percentage of student KKM achievement that is equal to 92% meets the effective criteria and the average difference test (t test) is obtained that tcount> ttable, which is 16.976> 1.677 and the significance value is <0.05. These results indicate that the developed learning tools are effective in improving students mathematical communication skills.

This research aims to know the effect of using LKPD based of Problem Based Learning model in improving Mathematical Communication Ability of Grade VIII Students at Dwi Sejahtera Junior High School Pekanbaru. The type of this research was Quasi Experimental Research with pretest-posttest control group design. The population was all students of Dwi Sejahtera Junior High School Pekanbaru Academic Year 2019/2020. The samples selection was conducted by using random sampling technique. Based on the result of data analysis, obtained the average score of posttest in Experimental Class 90,87, and the average score of the Control Class is 48,67. It means the average of Experimental Class is higher than the Control Class. The difference test of both averages used t-test obtained significance (2-tailed) 0,000 < α = 0,05 which means the average of posttest score of students’ Mathematical Communication Ability who learn by using LKPD based of PBL is different from the average score of posttest of students’ Mathematical Communication Ability who learn by using scientific learning model. Thus, it can be concluded that there is effect of Problem Based Learning model on students’ Mathematics Communication Ability.