New
New
Year 10
•
Higher
Describing a negative enlargement
I can describe an enlargement.
New
New
Year 10
•
Higher
Describing a negative enlargement
I can describe an enlargement.
These resources will be removed by end of Summer Term 2025.
Switch to our new teaching resources now - designed by teachers and leading subject experts, and tested in classrooms.
Lesson details
Key learning points
- If the image is the opposite side of the centre of enlargement and rotated 180°, there is a negative scale factor.
- If the image has changed size, there has been an enlargement with scale factor ≠ 1.
- To describe an enlargement, you must state the centre of enlargement and the 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.
Absolute value - The absolute value of a number is its distance from zero.
Common misconception
Pupils may want to write the transformation as two transformations, a rotation of 180° followed by an enlargement by a positive scale factor, rather than a single transformation.
Remind pupils that a single transformation is more efficient than multiple transformations.
Have pupils discuss how they can be sure that an enlargement by a negative scale factor has occurred rather than a rotation.
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
Loading...
Starter quiz
Download starter quiz
6 Questions
Q1.
When the scale factor of an enlargement is negative, the image is a of 180° of the object.
Correct Answer: rotation, -ve
rotation, -ve
Q2.
Which diagram shows an enlargement by a positive scale factor?
Correct Answer: An image in a quiz
Q3.
Sam enlarges a shape. The image is smaller than the object and the orientation is different. Which of these statements is correct?
Sam's scale factor is less than -1
Sam's scale factor is greater than -1
Sam's scale factor is between -1 and 1
Sam's scale factor is between 0 and 1
Correct answer: Sam's scale factor is between -1 and 0
Sam's scale factor is between -1 and 0
Q4.
Shape A is enlarged by the scale factor $$-\frac{1}{3}$$ to give shape B. The scale factor that would map shape B back onto shape A is .
Correct Answer: -3, - 3, minus 3, negative 3
-3, - 3, minus 3, negative 3
Q5.
Shape B is enlarged to give shape A. What is the scale factor of the enlargement?
$$2$$
$$\frac{1}{2}$$
Correct answer: $$-\frac{1}{2}$$
$$-\frac{1}{2}$$
$$-2$$
Q6.
Shape A is transformed to give shape A. Describe the transformation fully.
An enlargement scale factor -0.5
An enlargement scale factor -2
Correct answer: An enlargement scale factor -3
An enlargement scale factor -3
Correct answer: centre (3, 3)
centre (3, 3)
centre (4, 4)
Exit quiz
Download exit quiz
6 Questions
Q1.
An enlargement will produce an image that is to the object.
Correct Answer: similar
similar
Q2.
Shape A is enlarged to give shape B. Shape B is smaller than shape A. This means that the scale factor is __________.
equal to -1
equal to 1
greater than -1
less than 1
Correct answer: between -1 and 1
between -1 and 1
Q3.
Which of these show an enlargement with a negative scale factor?
Correct Answer: An image in a quiz
Q4.
Shape A is enlarged to give shape B. The scale factor of this enlargement is .
Correct Answer: -2, minus 2, negative 2, - 2
-2, minus 2, negative 2, - 2
Q5.
Shape A is enlarged to give shape B. Describe the transformation.
An enlargement scale factor $$2$$, centre $$(3, 2)$$
Correct answer: An enlargement scale factor $$\frac{1}{2}$$, centre $$(2, 3)$$
An enlargement scale factor $$\frac{1}{2}$$, centre $$(2, 3)$$
An enlargement scale factor $$-2$$, centre $$(2, 3)$$
An enlargement scale factor $$-\frac{1}{2}$$, centre $$(2, 3)$$
An enlargement scale factor $$\frac{1}{2}$$, centre $$(3, 2)$$
Q6.
Shape A is transformed to give shape B. Describe the transformation.
An enlargement scale factor $$2$$, centre $$(1, 2)$$
An enlargement scale factor $$\frac{1}{2}$$, centre $$(0, 2)$$
An enlargement scale factor $$-2$$, centre $$(0, 2)$$
Correct answer: An enlargement scale factor $$-2$$, centre $$(1, 2)$$
An enlargement scale factor $$-2$$, centre $$(1, 2)$$
An enlargement scale factor $$-\frac{1}{2}$$, centre $$(1, 2)$$