This study was aimed to: (1) describe the process of good instructional tools development, (2) describe the result of good instructional tools development, (3) describe the effectiveness of TS-TS cooperative learning with Problem Posing approach on the Parallelogram, especially for Rectangle and Square. Development research model proposed by Plomp (2013). The subjects were teacher and mathematics students of class VII MTs. Assholach, Pasuruan.  Instructional tools included lesson plan, students’ worksheets containing problem posing activities using “tree of mathematicsâ€, and test of learning outcome. Learning topics comprised characteristic, perimeter, and area of Rectangle and Square. The results of trial phase showed that the teaching materials were valid, practical and effective. The result of implementation phase showed that the TS-TS type of cooperative learning combined with Problem Posing approach is effective to teach the material of Rectangle and square in class VII.