terested in further research is developing the aforementioned findings into creating tools for exploring students’ metacogni- tive strategies in order to survey and study how students devel- oped metacognitive strategies in open-ended problem situations. In addition, it includes contextual factors affecting development of students’ metacognitive strategies in the mathematic class-room, using the innovation of lesson study and open approach in three areas: the structure of teaching and learning activities in the class, the teacher’ s intervention and interaction with stu-dents, and interaction between students. The research team plans to explore these areas for further study