This research was aimed at improving the mathematic problem solving
skill of VII-D grade students in SMP N 1 Rembang through Problem-based
Learning model by means of open-ended problem approach. This was classroom
action research done in 3 cycles. In each cycle, there were planning, acting,
observing, evaluating, and reflecting. The subject of this research was the students
of grade VII-D in SMP N 1 Rembang consisting of 36 students. The data werw
collected through evaluation test in the end of each cycle. The result of this
research showed that there was an improvement of the mathematic problem
solving skill. The improvement was shown by the fact that the average score in
the first cycle 61,77 increased to 74,71 in the second cycle, and again to 81,87 in
the third cycle. Based on the result, it could be concluded that the Problem-based
Learning with open-ended problem approach could improve the mathematic
problem solving skill of the VII-D grade students at SMP N 1 Rembang on lines
and angel material.