Learn · Illustrative Mathematics K–5 · Grade 3 · Unit 7
Short lessons you can play with. Sort shapes by their sides and right angles, find what makes a quadrilateral, tell rhombuses, rectangles, and squares apart, walk around shapes to find their perimeter, compare area and perimeter, and design with rectangles, then check yourself.
Seven short chapters follow the unit’s lessons in order. Each step shows one idea with something to tap or move, then a quick check. A wrong answer names the likely mistake and gives one more try. Progress is saved on this device.
Side lengths are whole numbers, and shapes with slanted sides are drawn to scale. Perimeters stay small enough to add in your head.
Right angle: a square corner, marked with a little square. Quadrilateral: a closed shape with 4 straight sides. Rhombus: a quadrilateral with 4 sides the same length. Rectangle: a quadrilateral with 4 right angles. Square: both a rhombus and a rectangle. Perimeter: the distance around a shape. Area: the space inside it, in square units.
Lessons 13 to 15 end the unit with open design projects (a playground, wax prints, a robot). The last chapter practices their math, but not the open designing. Practice it all in Playground Planners, the game for this unit.