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.