Open Approach which the lesson plans were written together every week.
Phase 2: Collaboratively observing the research lessons (do), during this session, the details of phase 1 in writing the lesson management plans, were used in classroom. A teacher in team was a representative of teaching. The rest of members were classroom observers or witnesses in teaching sequence using the 4 phases of Open Approach including: 1) Posing open-ended problem; 2) Students’ self learning through problem solving while the teacher take notes students’ idea for later discussion; 3) Whole class discussion and comparison; and 4) Summariza-tion through connecting students’ mathematical ideas emerged in the classroom aiming to observe mathematical approach of students communicating by gestures expressing during the phase of self learning, and group discussion. The teacher’s teaching ability wasn’t considered. The audio tape and video tape were recorded during sequence of teaching