After students have worked on the Triangles task in small groups, the teacher, Cindy, asks the class to discuss the rule t + 2 and where the +2 comes from the visual and symbolic representations. Near the end of the discussion, Lindsey poses the question, ‘Why isn’t it plus 4?’
Pose Purposeful Questions
Lulu’s Group
Lulu shares her group’s equation, n = (s + 2)^2 – s^2, explaining that it describes finding the area of the larger square (side length s + 2), then subtracting the area of the pool (side length s). Debra (the teacher) asks another student to paraphrase Lulu’s group’s approach.
Reymond’s Method
After a class discussion in which a few students have shared their equations for Regina’s Logo, the teacher, Gisele, invites Reymond to the board to explain how he obtained his algebraic equation visually from the geometric model.