Third Grade · Math · week 28

Area by tiling and by multiplying

Measure area by counting unit squares and by multiplying length × width.

Area is the amount of flat space a shape covers, measured in square units. You can find it by tiling the shape with unit squares and counting them — no gaps, no overlaps.

For a rectangle there is a shortcut: multiply the length by the width. A 4-by-3 rectangle has 4 rows of 3 squares = 4 × 3 = 12 square units. Tiling and multiplying always agree.

📋 For the teacher
Teach it (10–15 min):
  • Tile a real rectangle with square tiles or sticky notes, then multiply — prove they match.
  • Connect area straight back to arrays from week 2.
  • Insist on the word "square units" so area is not confused with length.
  • No gaps or overlaps — the tiles must cover exactly.
Talk about it:
  • What is area measured in?
  • How is finding area like an array?
  • Why does length × width work?

Mastery looks like: They find rectangle area by tiling and by multiplying, using square units.

Common stumbles: Counting only the border; forgetting "square" units; leaving gaps when tiling.

See it visually

Interactive, spoken-aloud tools that show this idea in motion.

MultiplicationEqual groups and arrays make products finally click.try →Counting & Ten-FramesCount objects in ten-frames and base-ten blocks, one tap at a time.try →
Homework for this lessonType it, write it with a stylus, or print it for pencil & paper.open →
Records attendance + 15 min of Math for this learner.
← Back to todayAll coursesYear planner