A three-part lesson is an inquiry-based learning method used to teach mathematics in K–12 schools. The three-part lesson has been attributed to John A. Van de Walle, a mathematician at Virginia Commonwealth University. The purpose is to cognitively prepare students for the math lesson by having them think about a procedure, strategy or concept used in a prior lesson. Teachers determine what specific previous learning they wish students to recall, based on outcomes desired for that particular lesson. The role of the teacher is to "get students mentally prepared to work on the problem". Marian Small, a proponent of a constructivist approach to mathematical instruction, provides an example of an inquiry-based question from which a three-part lesson could be created: "one bus has 47 students in it; another has 38. How many students are on both buses?" Students engage in solving math problems individually, in pairs, or in small groups, and "record the mathematical thinking they used to develop solutions". Students then plan the strategies, methods, and concrete materials they will use to solve the problem. The teacher will circulate and make observations about the ways students are interacting, and will note the mathematical language they are using as well as the mathematical models they are employing to solve the problem. If a student is having difficulty, "the teacher might pose questions to provoke further thinking or have other students explain their plan for solving the problem". Teachers are advised to be active listeners in this phase, and to take notes. This is also a phase in which teachers can assess students. In this final phase, the teacher oversees the sharing of solutions by students, and may employ other teaching techniques such as "math congress", "gallery walk", or "bansho". If new methods and strategies were discovered by students during the work phase, the teacher will post these on the class's "strategy wall", or use them to develop an "anchor chart".
Alfred Rufer, Daniel Siemaszko, Lukas Fleischli, Frédéric Zurkinden