IMPROVING STUDENTS MATHEMATICAL PROBLEM SOLVING ABILITY BY USING COOPERATIVE LEARNING MODEL TYPE NUMBERED HEADS TOGETHER AT SMA NEGERI 1 PERBAUNGAN

The objectives of this research were: (1) To know whether Cooperative
Learning model type Numbered Heads Together (NHT) can improve students’
mathematical problem solving; (2) To know the effectiveness of Cooperative
Learning model type Numbered Heads Together (NHT) to improve students’
mathematical problem solving ability at SMA Negeri 1 Perbaungan. Type of the
research was Classroom Action Research (CAR). The subjects were students of grade
XI MIA-1 that consist of 34 students. The object was students’ mathematical problem
solving ability.
The research was conducted in 2 cycles. Every cycle consisted of 2 meetings.
Students’ mathematical problem solving ability test was given at the end of each
cycle. The finding of this study were: (1) Mathematical problem solving ability of
students in the first cycle have average class score was 2.72 at the scale 1-4, from 34
students only 21 students have achieved mastery level, and categorized moderate
ability (2) Mathematical problem solving ability of students in the second cycle have
average class score 3.15 at scale 1-4, and 31 students have achieved mastery level and
categorized high ability. From the results it can be concluded that the implementation
of the Cooperative Learning model type Numbered Heads Together (NHT) can
improve the students’ mathematical problem solving ability.