New
New
Year 6

Describe the relationship between scale factors and perimeters of two shapes

I can describe the relationship between scale factors and side lengths and perimeters of two shapes.

New
New
Year 6

Describe the relationship between scale factors and perimeters of two shapes

I can describe the relationship between scale factors and side lengths and perimeters of two shapes.

Lesson details

Key learning points

  1. If the lengths of the sides of a shape have been doubled, the perimeter will be double.
  2. If the side lengths of a shape are multiplied by the same factor the perimeter will be multiplied by the same factor.
  3. The number which all the sides have been multiplied by is called a scale factor.

Keywords

  • Perimeter - Perimeter is the distance around a two-dimensional shape.

  • Scale factor - A scale factor is the multiplier between similar shapes that describes how large one shape is compared to the other.

  • Similar - Two shapes are similar when one shape can become the other after a resize, flip, slide or turn.

Common misconception

Pupils may remember to scale one of the sides (or pairs of sides) of a shape but forget to scale the others.

Focus attention on what it means when a shape is similar, drawing on examples and non-examples to support learners to understand how scaling affects all side lengths.

Providing to-scale examples of scaled polygons initially may support all learners to practically see and measure the scaling that has taken place.
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).

Lesson video

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6 Questions

Q1.
Double 17 is
Correct Answer: 34
Q2.
Multiply 16 by 4
Correct Answer: 64
Q3.
Which of these is the same as dividing by two?
Dividing by one-half
Correct answer: Multiplying by one-half
Adding one-half
Multiplying by one-quarter
Q4.
Match the words to their correct definitions.
Correct Answer:Transform ,Change something

Change something

Correct Answer:Enlarge ,Make something larger

Make something larger

Correct Answer:Reduce ,Make something smaller

Make something smaller

Q5.
Match the equations to the correct product.
Correct Answer:5 × 6 = ,30

30

Correct Answer:4 × 7 = ,28

28

Correct Answer:12 × 2 = ,24

24

Correct Answer:3 × 9 =,27

27

Q6.
Which of the following are multiples of 7?
Correct answer: 28
34
40
Correct answer: 42
Correct answer: 49

6 Questions

Q1.
Select all of the scale factors where the result would be a shape with a greater length and width than the original.
Scale factor of 1
Scale factor of one-half
Correct answer: Scale factor of 2
Scale factor of one-third
Correct answer: Scale factor of 3
Q2.
Shape A is a square with a side length of 3 cm and Shape B is a square with a side length of 12 cm. Shape A has been scaled by a scale factor of to create Shape B.
Correct Answer: 4, four
Q3.
Shape A is an equilateral triangle with a side length of 3 cm and Shape B is an equilateral triangle with a side length of 9 cm. Shape A has been scaled by a scale factor of to create Shape B.
Correct Answer: 3, three
Q4.
Shape A is a square with a side length of 3 cm which has been scaled by a scale factor of 3 to get Shape B. What is the perimeter of Shape B? cm.
Correct Answer: 36
Q5.
Shape A is a triangle with a side length of 3 cm which has been scaled by a scale factor of 4 to get Shape B. What is the perimeter of Shape B? cm.
Correct Answer: 36
Q6.
Select all of the scale factors where the result would be a shape with a smaller length and width than the original.
Correct answer: Scale factor of one-half
Scale factor of 2
Correct answer: Scale factor of one-third
Scale factor of 3
Correct answer: Scale factor of one-quarter