Learn · Illustrative Mathematics K–5 · Grade 3 · Unit 2
Short lessons you can play with. See area as the number of squares that cover a shape, multiply to find the area of a rectangle, choose the right square units, cut rectangles in two to use facts you know, and find the area of figures made of rectangles, then check yourself.
Eight 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 go up to 10 and areas stay within 100, so every multiplication is a fact within 10 × 10. As in class, a rectangle with 4 rows of 6 squares is 4 × 6.
Area: how much space a flat shape covers, counted in squares. Square unit: a square 1 unit on each side, like a square centimeter or a square foot. Gaps and overlaps: spaces left uncovered, and tiles on top of each other; both make a count wrong. Side length: how long a side is. Perimeter: the distance around a shape, which is not its area.
Area and the Multiplication Table (Lesson 11) and New Room (Lesson 15) are optional lessons. Practice it all in Tile Town, the game for this unit.