As students move to thinking about formulas it supports their conceptual knowledge of how the perimeter of rectangles can be put into general form.What formula below displays a common student error for finding the perimeter?
A)P = l + w + l + w
B)P = l + w
C)P = 2l + 2w
D)P = 2(l + w)

Question

Quizplus · Accepted Answer

The correct formula for the perimeter of a rectangle is P = 2l + 2w or P = 2(l + w), which accounts for both pairs of sides. Choice B, P = l + w, represents a common student error by only adding one length and one width, thus not accounting for all sides of the rectangle.

As Students Move to Thinking About Formulas It Supports Their