THE IMPLEMENTATION OF GROUP INVESTIGATION LEARNING MODEL TO IMPROVE THE STUDENTS MATHEMATICAL COMMUNICATION ABILITY OF EIGHT GRADE SMP N 4P.SIANTAR ACADEMIC YEAR 2014/2015

The purpose of this research were (1) to find out how the group investigation learning model can improve the students mathematical communication ability, (2) to determine whether students mathematical communication ability increased after implementing the group investigation learning model, (3) to determine the students attitudes toward mathematics learning using the group investigation learning model. The type of his research was belongs to Classroom Action Research (CAR), which was implemented in SMP Negeri 4 Pematangsiantar. The subject in this research were the students of class VIII-5 in 2014/2015 that have total were 32 students consisting of 12 men and 20 women. The objects of this resarch are the students mathematical communiation ability and group investigative learning model. This research consisted of 2 cycles and from the first cycle consists of 2 meetings and the second cycle consists of 2 meetings. The students mathematical communication ability test conducted at the end of each cycle. The results of this research could be seen: (1) The results of students mathematical communication ability tests in the first cycle known average value was 42,19, complete 9 students, incomplete 23 students, 28,125% classical completeness and the students mathematical communication ability categorized was very low. (2) The results of students mathematical communication ability tests in the second cycle known average value was 75,81, complete 28 students, 4 students incomplete, 87,50% classical completeness and students mathematical communication ability was middle categorized. (3) Learning by using the group investigation learning model could make the students activity was good categorized in learning, and (4) Learning by using the group investigation learning model could provide a positive attitude to the students in the learning process. From the results of this research could be concluded that the implementation of the group investigative learning model can improve the students mathematical communication ability. The suggestion given for teachers were to be able to implement the group investigative learning model as an alternative in the learning process that can improve the communication skills.