In Thailand, the Center for Research in Mathematics Education (CRME) has been implementing Japanese Lesson Study (LS) since 2002. An adaptive feature of this implementation was the incorporation of four phases of the Open Approach as a teaching approach within the three steps of the LS process. Four phases of this open approach are: 1) Posing open-ended problem, 2) Students' self learning, 3) Whole class discussion and comparison, and 4) Summing-up by connecting students' emergent mathematical ideas. The three phases of the LS model were: collaboratively design a research lesson; collaboratively observe the research lesson; and collaboratively discuss and reflect on the research lesson. In the research project run by CRME across the country, LS teams have been facing the problem of how to engage students with self learning in the second phase. The LS teams planned the research lesson with an emphasis on "how to learn" which was a key influence for engaging students in the self learning phase (i.e. students' problem solving). This paper is mainly descriptive of the features of the adaptive LS in a school context but presents a snippet of evidence where students successfully use "how to learn" sections from the "decomposing unit" in the "Addition unit". (Contains 7 figures and 1 footnote.)