Illustrative Mathematics K–5 · Grade 3 · Unit 7 · Two-dimensional Shapes and Perimeter
The town is building a new playground, and you’re on the planning team! Sort shapes at the Shape Sorter, name quadrilaterals at Kite Corner, walk the Chalk Trail, measure the Fence Line, plan the Sandbox, and design robots in the Design Studio. Then open the playground at the Grand Opening. Each station matches lessons from class.
Each station deals 8 fresh problems (the Grand Opening deals 10). A right answer on the first try earns 10 points. After a wrong answer, the game names the likely mistake and gives one more try for 5 points. In the Grand Opening, each right answer raises a flag over the playground.
Hints use the pictures from class: shapes with their right angles marked and their side lengths written, shapes on a grid with each unit length around the outside numbered, rectangles with their sides, and figures made of rectangles. A used hint caps that problem at 5 points.
Counting every corner as a right angle, calling an open or curved shape a quadrilateral, thinking a square isn’t a rectangle or a rhombus, mixing up rhombuses and rectangles, counting the squares inside instead of the length around, counting a shape’s sides instead of its unit lengths, adding only one length and one width of a rectangle, leaving out a side, multiplying for the perimeter, forgetting to take the known sides away from the perimeter, and stopping at the width in a two-step problem.
Side lengths are whole numbers, in centimeters, meters, inches, or feet, and perimeters stay at 60 or less. Shapes with slanted sides are drawn to scale. Areas are under 100 square units.
Each station matches a chapter of the Learn page for this unit, which walks through the ideas step by step.
Lessons 13 to 15 end the unit with open design projects (a playground, wax prints, a robot). The Design Studio practices their math, perimeter and area of designs made of rectangles, but not the open designing.