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Lesson 8 of 9

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Six ideas, seven checks. The table first, so you have somewhere to look back.

Perimeter and Area — walk it, tile it, split it
MoveHow it goes
Find a perimeterWalk every side once, add the lengths.
Shortcut for a rectangle2 × (length + breadth).
Find an areaCount whole unit squares, no gaps, no overlaps.
Area of a rectanglelength × breadth.
Compare two pensSame rope does not mean the same area.
Split an odd shapeBreak it into rectangles, then add their areas.

You walk all the way around a courtyard. You add up every side. What have you found?

  • The area of the courtyard
  • The perimeter of the courtyard
  • The number of corners the courtyard has

A rectangle is 9 cm long and 5 cm wide. What is its perimeter?

  • 45 cm
  • 28 cm
  • 14 cm

A rectangle has a perimeter of 20 cm. Its length is 6 cm. What is its breadth?

  • 14 cm
  • 10 cm
  • 4 cm

A shape is tiled with 15 unit squares. Each is 1 cm by 1 cm. No gaps, no overlaps. What is its area?

  • 15 cm
  • 15 cm²
  • 15

A rectangle is 8 cm long and 3 cm wide. What is its area?

  • 11 cm²
  • 24 cm²
  • 22 cm²

Two pens are each fenced with 20 m of rope. One is a 5 m square. The other is 8 m by 2 m. What is true about their areas?

  • They must be equal, since the rope length is equal
  • They can be different — a fixed perimeter does not fix the area
  • The longer, thinner pen always has the bigger area

A room is shaped like an L. A smaller room is cut out of one corner. What is the safest way to find its floor area?

  • Multiply the room's two outer edges, ignoring the cut corner
  • Split it into plain rectangles, find each area, then add them up
  • Guess, since an L-shape has no real area

That is Chapter 6, Perimeter and Area, in your NCERT book. You measured both before you read either.

Next: Fractions. Equal parts of one whole. And the two numbers that name a part.

Reveal every answer to finish this lesson.