In Topic E, students solve problems with perimeter and area. Lesson 23 focuses on solving a variety of word problems involving perimeter. This provides students an opportunity to use multiplication and division strategies to solve problems about perimeter.
Students use rectangles and circles to measure, create, and analyze robots and environments for the robots using specified perimeter measurements in Lessons 24 through 27. They reason about the different whole number side lengths that may be produced. For example, when given the requirement that the perimeter of the arms of the robot must be 14 inches, students experiment and draw different possibilities for rectangles to determine which ones they prefer for the robot’s arms based on their explorations with unit squares in Topic D. Students cut out and assemble the parts of the robot from grid or construction paper, and compare their robots with their peers’. The final lesson in this sequence provides an opportunity for peer review and critique, and also for discussion about the difference between the areas of robots and their environments despite the fact that they have the same given perimeters.