New
New
Year 10
Higher

Checking and securing understanding of enlargement with positive integer scale factors

I can describe an enlargement and perform a given enlargement on an object.

New
New
Year 10
Higher

Checking and securing understanding of enlargement with positive integer scale factors

I can describe an enlargement and perform a given enlargement on an object.

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Lesson details

Key learning points

  1. Each length in the shape is multiplied by the scale factor.
  2. Each vertex in the object is a given distance from the centre of enlargement.
  3. This distance is also multiplied by the scale factor to give the distance of the image's vertex.
  4. A positive integer scale factor produces an image that is bigger than the original.
  5. To enlarge, you need the centre of enlargement and a scale factor.

Keywords

  • Transformation - A transformation is a process that may change the size, orientation or position of a shape.

  • Enlargement - Enlargement is a transformation that causes a change of size.

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

  • Centre of enlargement - The centre of enlargement is the point from which a shape is enlarged.

Common misconception

Pupils may measure/count from the object rather than the centre of enlargement.

Have pupils check their answers using ray lines.

Discuss how enlargements create similar shapes that are not congruent on the most part, whereas rotation, reflection and translation always create congruent shapes. When can an enlargement create congruent shapes?
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.
A of a shape is the mirror image of the shape.
Correct Answer: reflection
Q2.
Which of these diagrams do NOT show a reflection?
Correct Answer: An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
An image in a quiz
Q3.
Two shapes are similar if the only difference between them is their __________. Their side lengths are in the same proportions.
angles
orientation
position
Correct answer: size
vertices
Q4.
Which of these diagrams show a reflection?
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
Q5.
Quadrilaterals A and B are similar. The length of the side marked $$z$$ is cm.
An image in a quiz
Correct Answer: 8, 8cm, 8 cm
Q6.
Rectangle B is an enlargement of rectangle A by scale factor 2. Rectangle A has perimeter = 18 cm and area = 18 cm². Both rectangles have integer side lengths. Find the area and perimeter of B.
An image in a quiz
Area = 36 cm²
Correct answer: Area = 72 cm²
Correct answer: Perimeter = 36 cm
Perimeter = 72 cm

6 Questions

Q1.
An enlargement will produce an image that is __________ to the object.
congruent
Correct answer: similar
Q2.
Shape A is enlarged to give shape B. The scale factor of this enlargement is .
An image in a quiz
Correct Answer: 3, three
Q3.
These two shapes are an enlargement of each other. The missing length is cm.
An image in a quiz
Correct Answer: 6, six, 6 cm, 6cm
Q4.
Shape A is enlarged to give shape B. The scale factor of this enlargement is .
An image in a quiz
Correct Answer: 2, two
Q5.
Shape A is enlarged to give shape B. What is the centre of the enlargement?
An image in a quiz
(0, 0)
Correct answer: (1, 0)
(0, 1)
(1, 1)
(2, 1)
Q6.
Shape A is enlarged by scale factor 2, centre (6, 6) to give shape B. Select the points that should be joined to give shape B.
An image in a quiz
Correct answer: (2, 4)
(0, 4)
(4, 4)
Correct answer: (4, 0)
Correct answer: (2, 0)