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      Checking and securing understanding of perimeter for standard shapes

      Lesson details

      Learning outcome

      I can calculate the perimeter of rectangles, triangles, parallelograms and trapeziums efficiently.

      Key learning points

      1. The perimeter of any polygon can be found by adding but this may be time consuming.
      2. By considering the properties of the shape, there may be a more efficient method.
      3. There is a formula to find the perimeter of rectangle.
      4. Missing side lengths can be found if the perimeter is known.

      Keywords

      • Perimeter - The perimeter is the distance around a 2D shape.

      • Polygon - A polygon is a flat (2D), closed figure made up of straight line segments.

      Common misconception

      "To find the perimeter, you just add together the numbers that you see."

      The perimeter of a polygon is the sum of the lengths of all the sides of that shape. Not all sides have their lengths explicitly written. This could be due to sides having equal length, and the lengths of some sides shown with hash marks.

      Teacher tip

      It can be helpful to encourage students to systematically go around the edges of a polygon one by one to check if its side lengths are known (or can be found out) before explicitly finding the perimeter of that shape.

      Licence

      This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0
      except where otherwise stated. See Oak's terms & conditions
      (Collection 2).

      Lesson video

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      Prior knowledge starter quiz

      6 Questions

      Q1.
      The is the distance around a 2D shape.

      Correct Answer: perimeter

      Q2.
      Which units can be used for perimeter?

      Correct answer: cm
      cm²
      cm³
      grams
      litres

      Q3.
      1 cup is equivalent to 16 tablespoons. A quarter of a cup is equivalent to tablespoons.

      Correct Answer: 4, four

      Q4.
      Approximately 28 grams are equivalent to 1 ounce (oz). There are 16 ounces in a pound. 1 pound is approximately __________ grams.

      1.75
      12
      44
      Correct answer: 448

      Q5.
      1 kilometre = centimetres.

      Correct Answer: 100 000, 100000, 100,000, one hundred thousand, 100 thousand

      Q6.
      Starting with the smallest length, put the lengths in order of size.

      1 - 35 000 mm
      2 - 0.35 km
      3 - 350 000 cm
      4 - 35 000 m

      6 Questions

      Q1.
      The perimeter of the rectangle is cm.

      An image in a quiz
      Correct Answer: 50, fifty, 50 cm

      Q2.
      The perimeter of the parallelogram is __________ units.

      An image in a quiz
      7
      8
      12
      14
      Correct answer: 16

      Q3.
      The perimeter of the trapezium is 26 units. The length of the sloping side is units.

      An image in a quiz
      Correct Answer: 8, eight

      Q4.
      The regular hexagon has perimeter 30 cm. $$a$$ = .

      An image in a quiz
      Correct Answer: 5, five, 5 cm

      Q5.
      Jacob draws a rectangle. Sofia draw a parallelogram (without right angles). Each shape has the same base and height. Which statement is true?

      The rectangle has a greater perimeter than the parallelogram.
      Correct answer: The parallelogram has a greater perimeter than the rectangle.
      Both shapes have the same perimeter.

      Q6.
      The perimeter of the rectangle is 28 cm. $$m$$ = .

      An image in a quiz
      Correct Answer: 6, six, 6 cm

      To help you plan your 10 maths lesson on: Checking and securing understanding of perimeter for standard shapes, download all teaching resources for free and adapt to suit your pupils' needs...