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Year 10
Foundation

Checking and securing understanding of perimeter for compound shapes

I can calculate the perimeter of compound shapes made from rectangles, triangles, parallelograms and trapeziums efficiently.

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Share activities with pupils
New
New
Year 10
Foundation

Checking and securing understanding of perimeter for compound shapes

I can calculate the perimeter of compound shapes made from rectangles, triangles, parallelograms and trapeziums efficiently.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. Before calculating perimeter, consider the shape and check you know the required lengths.
  2. It is not necessary to know every side length.
  3. Sometimes you can deduce the sum of a subset of side lengths.
  4. Identifying where you can be more efficient can make calculations simpler.

Common misconception

Pupils may miss an edge when calculating the perimeter.

Encourage the pupils to trace the perimeter to check that all edges have been included in the sum.

Keywords

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

  • Compound shapes - A compound shape is a shape created using two or more basic shapes.

  • Composite shapes - A composite shape is an alternative for a compound shape.

This lesson involves Pythagoras' theorem and properties of shape, so you may wish to set a homework revisiting these skills in preparation for the lesson.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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Starter quiz

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6 Questions

Q1.
The __________ is the distance around a 2D shape.
area
Correct answer: perimeter
volume
Q2.
The perimeter of this rectangle is cm.
An image in a quiz
Correct Answer: 14, fourteen, 14 cm, 14cm
Q3.
The perimeter of this parallelogram is cm.
An image in a quiz
Correct Answer: 16.6, 16.6 cm, 16.6cm
Q4.
The perimeter of this triangle is cm.
An image in a quiz
Correct Answer: 45, forty five, 45 cm, 45cm
Q5.
Which of these shapes has different perimeter to the other three shapes?
An image in a quiz
An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
Q6.
The length of the edge marked 'a' is cm.
An image in a quiz
Correct Answer: 1.5, one and a half, 1.5 cm, 1.5cm

Exit quiz

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6 Questions

Q1.
Which of the following are examples of compound shapes?
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
Q2.
The perimeter of this compound shape is cm.
An image in a quiz
Correct Answer: 33, thirty three, 33 cm, 33cm
Q3.
The perimeter of this compound shape is cm.
An image in a quiz
Correct Answer: 28, twenty eight, 28 cm, 28cm
Q4.
The perimeter of this compound shape is cm.
An image in a quiz
Correct Answer: 64.4
Q5.
Match the marked edges with the correct calculations.
An image in a quiz
Correct Answer:$$a$$,$$4 + c$$

$$4 + c$$

Correct Answer:$$b$$,$$8 − 3$$

$$8 − 3$$

Correct Answer:$$c$$,$$\sqrt{5^2-3^2}$$

$$\sqrt{5^2-3^2}$$

Correct Answer:$$d$$,$$\sqrt{\text{b}^2+12^2}$$

$$\sqrt{\text{b}^2+12^2}$$

Q6.
The perimeter of this compound shape is cm.
An image in a quiz
Correct Answer: 56, fifty six, 56 cm, 56cm