There have been many attempts to transform the nature of classroom teaching toward the inquiry-based approach. In inquiry-based lessons, students are asked to examine diverse approaches to solve open-ended problems and develop a new understanding through problem solving (Foss & Kleinsasser, 1996; Kinach, 2002; Tillema & Knol, 1997). However, for teachers, incorporating inquiry-based problem solving poses a variety of pedagogical challenges. For instance, to promote students' inquiry, teachers might ask the students to find their own ways to calculate 2/3 of 24 tomatoes before teaching the standard algorithm to solve the problem. In response, the students could construct their own strategies to generate their answers (e.g., 2 x 24 ÷ 3, 24 ÷ 3 x 2, etc.). But the students could respond with inefficient strategies (e.g., 2/3 + 2/3 + ... + 2/3) or inappropriate strategies (e.g., ‘‘0.6 x 24’’).

The question is how the teacher should respond in such cases. Simply telling the right answer to the students could turn off the students’ personal sense-making and possibly reduce the inquiry lesson to the one-directional knowledge transmission model. However, if the weakness of the strategy is not addressed, this might create an ‘‘everyone is right’’ norm in which the students’ problem solving is not critically examined or challenged.

Obviously, the answer does not lie in these extreme cases: In inquiry lessons, a teacher’s role should be to help the students negotiate different meanings and assumptions with others and internalize new perspectives (Stein, Engle, Smith & Huges, 2008). However, in reality, interacting with each individual student and addressing all inefficient or wrong strategies can be time-consuming and challenging in classroom situations. As a result, inquiry lessons may end up with  “show and tell” in which students merely take turns sharing their ideas and strategies without critically examining diverse ideas that were shared (Ball, 2001; Lampert, 2001; Stein et al. 2008).

In Japanese schools, teachers learn to overcome this pedagogical challenge by engaging in lesson study that is institutionalized across schools. There, Japanese teachers collaborate with other teachers to plan, observe and reflect on inquiry lessons that often involve four key components (Fernandez & Yoshida, 2004; Stigler & Hiebert, 1999). They are: 1) hatsumon (initial question/problem that the teacher gives to initiate a rich inquiry-based problem solving), 2) kikanjyushi (students’ individual or group-based problem solving as the teacher walks by their desks to observe and interact with the students), 3) neriage (whole class discussions to compare and contrast different strategies and build consensus on the problem solving and key concepts), and 4) matome (theorizing key ideas and applications of the ideas to new problems). Among the four components, the neriage is considered to be the most crucial stage (Fernandez & Yoshida 2004; Shimizu 1999, Takahashi, 2006). Neriage literally translates as “kneading up.” For neriage, teachers have their students first present their ideas and then orchestrate the classroom discussion to “knead up” students’ ideas as they build consensus with their peers. The whole-class discussion serves as a “climax” of the inquiry-based lessons where teachers create structured opportunities for students to socially deconstruct logic, compare and contrast different ideas, and weighing evidence of an assertion to draw a valid conclusion (Inoue, 2010).

Then the questions are, how do Japanese elementary school teachers actually implement this social pedagogy in their classrooms? More importantly, what characterize the teacher expertize that underlies the decision-making and actions in implementing successful neriage? These questions served as the research questions for this study. Answering these research questions could reveal previously unknown aspects of teacher expertize needed to successfully implement inquiry-based lessons.

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