The Case of the Missing Sides!
Introduction to Perimeter: Students transform into Perimeter Detectives as they try to solve The Case of the Missing Sides! After they figure out the unknown side lengths of 10 real world irregular polygons, they must infer what they are part of!
Introduction (Fence for the Vegetable Garden)
Students are introduced to the term perimeter by relating it to a garden fence. Project the image of the garden and say, “I need to put up a fence around my vegetable garden to keep animals out, what would I need to know to build it?”
Perimeter Detective: The Case of the Missing Sides!
Students move around the room, investigating irregular polygons and figuring out the length of the missing side. Then, they infer what the photographs are of!
Irregular Polygon Images (perimeter and side lengths included):
Vegetable Garden (used for introduction)
People on the Beach
Reinforcement (Perimeter Detective Exit Slip and Self-Assessment)
For reinforcement, students apply their new skills independently by figuring out the missing side lengths of five irregular polygons. Then, they rate their understanding by drawing a checkmark in the box that fits their current knowledge of the content.
- This unit can be adapted for older students: have them convert measurement lengths to work with larger numbers - Conversion Chart included!
Math Common Core Standard
Strand: Measurement and Data
Topic: Geometric measurement: recognize perimeter.
Standard Statement: Solve real world and mathematical problems involving perimeters of polygons, including finding the perimeter given the side lengths, finding an unknown side length, and exhibiting rectangles with the same perimeter and different areas or with the same area and different perimeters.