Enlarging objects | Maths | Quizalize & Oak National Academy

Starter quiz

Scale factor is the ______ between similar shapes that describes how large one shape is compared to the other.

'multiplier' ✓
The invariant point from which an object is enlarged is known as the _________________.

'centre of enlargement' ✓
P has been enlarged to create A. What is the scale factor?

$1\over2$

2 ✓

8

16
P has been enlarged to create A. What is the value of $a$ ?

3

4

12

16 ✓
P has been enlarged to create B. What is the scale factor?

$1\over2$ ✓

2

3.5

7
P has been enlarged to create B. What is the value of $b$ $?

3.5

4 ✓

6

Which of these is NOT a method for enlarging an object?

measuring with a ruler

counting line length ✓

counting squares

marking one point
When enlarging, an image and object can overlap.

True ✓
False
$The shape is being enlarged by a scale factor of <Math>1\over2</Math>. The centre of enlargement is marked with a cross. What are the new coordinates of B?$

The shape is being enlarged by a scale factor of $1\over2$ . The centre of enlargement is marked with a cross. What are the new coordinates of B?

(16,6)

(12,6)

(8,6)

(7,6) ✓
When using lines to check the position of the image, the lines must

go through the centre of enlargement ✓

go through all of the vertices of the image

go through all of the vertices of the object

go through all of the vertices of both object and image ✓
When enlarging by a non-integer scale factor, the image is always smaller than the object.

True
False ✓
Jun is enlarging an object by a scale factor of $2{1\over2}$ . If one of the object's lengths is 5, what will the corresponding length be in the image?

$2{1\over2}$

5

$7{1\over2}$

$12{1\over2}$ ✓

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Each length in the shape is multiplied by the scale factor
Each vertex in the object is a given distance from the centre of enlargement
This distance is also multiplied by the scale factor to give the distance of the image's vertex

Pupils may initially be unsure when enlarging shapes on different background in Q2 of Task B.

Stress that they can use the same methods as for square or plain backgrounds (e.g. using a ruler, counting units along gridlines).

Centre of enlargement - The centre of enlargement is the point from which a shape is enlarged.
Scale factor - A scale factor is the multiplier between similar shapes that describes how large one shape is compared to the other.