Enlargement – Positive – Complete Lesson
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Label and join these points
To create a star:
(-5, 1), (-3, 1), (-6, 4),
(-2,4), (-4, 5)
Reflect the shape
in 𝑥 = −1
Label the new shape S’.
Reflect S’ in 𝑦 = 0.5
Label the new shape S’’
𝑥 = −1
Label and join these points
To create a star:
S’
(-5, 1), (-3, 1), (-6, 4),
(-2,4), (-4, 5)
𝑦 = 0.5
Reflect the shape
in 𝑥 = −1
Label the new shape S’.
S’’
Reflect S’ in 𝑦 = 0.5
Label the new shape S’’
NEALREG
ENLARGE
SZEI
SIZE
RTARFMOSN
TRANSFORM
APESH
SHAPE
CESLA FCORAT
SCALE FACTOR
EXRTVE
VERTEX
26 March 2025
Positive Enlargements
KNOWLEDGE CHECK
Describe the enlargement
A to B.
B
A
Describe the enlargement
B to A.
KNOWLEDGE CHECK
Describe the enlargement
A to B.
B
A
Scale Factor = 2
Centre of Enlargement = (-5,-5)
Describe the enlargement
B to A.
1
Scale Factor =
2
Centre of Enlargement = (-5,-5)
What have we multiplied the sides of A by, to get B?
5 cm
A
10 cm
B
2
The enlargement has a scale factor of 2.
Every enlargement has a scale factor.
It can be positive, negative and fractional.
(The height and length have doubled. But what has happened to the area?)
A
A
A
B
B
B
A
B
A
B
What scale factor does each
enlargement have? (A to B)
A
B
A
A
A
B
2
3
B
2
B
A
5
B
1
2
A
B
What scale factor does each
enlargement have? (A to B)
A
2
B
Every enlargement has a scale factor and a centre of enlargement.
①
Enlarge Shape A
by a scale factor of 2
from a centre of enlargement (3,4)
Counting Squares Method
We will count the squares to
each vertex and
double the distance
for the new shape.
6
4
2
3
B
23 A
4
6
CHECK 1!
We can check the enlargement
with a ruler.
The corresponding vertices
should be in a straight line.
CHECK 2!
Are the lengths all double?
Every enlargement has a scale factor and a centre of enlargement.
6
Enlarge Shape A
by a scale factor of 2
from a centre of enlargement (9,3)
8
3
B
4
2
2
A
1 1
6 43
②
2
Counting Squares Method
We will count the squares to
each vertex and
double the distance
for the new shape.
CHECK 1!
We can check the enlargement
with a ruler.
The corresponding vertices
should be in a straight line.
CHECK 2!
Are the lengths all double?
Every enlargement has a scale factor and a centre of enlargement.
Enlarge Shape A
by a scale factor of 3
from a centre of enlargement (10,3)
3
6
B
1
3
1
3
9
A
③
1
33 1
2
Counting Squares Method
We will count the squares to
each vertex and
triple the distance
for the new shape.
CHECK 1!
We can check the enlargement
with a ruler.
The corresponding vertices
should be in a straight line.
CHECK 2!
Are the lengths all double?
Every enlargement has a scale factor and a centre of enlargement.
2
4
1
2
④
Enlarge Shape A
by a scale factor of 2
from a centre of enlargement (2,11)
A
B
Do we need to plot all the vertices?
Counting Squares Method
We will count the squares to
each vertex and
double the distance
for the new shape.
Scale Factor = 2
Centre of Enlargement =
Describe
the enlargement
of shape A to B.
We can see
the dimensions
of the shape
have doubled.
B
A
(3,2)
Scale Factor = 3
Centre of Enlargement =
Describe
the enlargement
of shape A to B.
We can see
the dimensions
of the shape
have tripled.
B
A
(9,1)
1
Scale Factor =
2
Describe
the enlargement
of shape A to B.
We can see
the dimensions
of the shape
have halved.
Centre of Enlargement =
A
B
(3,1)
①
Enlarge Shape A
1
by a scale factor of
2
from a centre of enlargement (3,2)
CHECK 1!
The corresponding vertices
should be in a straight line.
CHECK 2!
Are the lengths all halved?
8
8
4
4
2
1
4
2
4
A
B
1
8
2
②
Enlarge Shape A
1
by a scale factor of
2
from a centre of enlargement (4,2)
A
CHECK 1!
The corresponding vertices
should be in a straight line.
CHECK 2!
Are the lengths all halved?
4
2
B
4
2
3
6
Positive Enlargements
1)
Enlarge shape A by a scale factor of 2.
Label the new shape A’
Enlarge shape B by a scale factor of 3.
Label the new shape B’
2)
Enlarge shape C by a scale factor of 2,
from centre of enlargement (2,1).
Label the new shape C’.
One of the new vertices has been done for you.
3)
①
Enlarge shape D by a scale factor of 3,
from centre of enlargement (2,10).
Label the new shape D’.
A
D
C
B
4) Describe the enlargement from shape E to E’.
5)
Enlarge shape F by a scale factor of 2,
from centre of enlargement (5,11).
Label the new shape F’.
6)
Enlarge shape G by a scale factor of
from centre of enlargement (3,1).
Label the new shape G’.
F
E’
E
G
1
,
2
Positive Enlargements
1)
Enlarge shape A by a scale factor of 2.
Label the new shape A’
Enlarge shape B by a scale factor of 3.
Label the new shape B’
2)
Enlarge shape C by a scale factor of 2,
from centre of enlargement (2,1).
Label the new shape C’.
One of the new vertices has been done for you.
3)
①
Enlarge shape D by a scale factor of 3,
from centre of enlargement (2,10).
Label the new shape D’.
A
D
C’
B’
A’
D’
C
B
4) Describe the enlargement from shape E to E’.
Scale Factor = 2
5)
Centre of Enlargement = (7,2)
Enlarge shape F by a scale factor of 2,
from centre of enlargement (5,11).
Label the new shape F’.
6)
Enlarge shape G by a scale factor of
from centre of enlargement (3,1).
Label the new shape G’.
F
E’
G
F’
E
Answers
G’
1
,
2
Positive & Fractional Enlargements
3) Describe these two enlargements of A to B
Enlarge shape A by a scale factor of 2,
1) from centre of enlargement (11,3).
2)
Label the new shape A’.
②
Enlarge shape B by a scale factor of 3,
from centre of enlargement (5,2).
Label the new shape B’.
B
A
B
A
4)
Enlarge shape C by a scale factor of
from centre of enlargement (11,4).
Label the new shape C’.
A
B
1
,
2
5)
Enlarge shape D by a scale factor of
from centre of enlargement (2,10).
Label the new shape D’.
1
,
3
6)
Enlarge shape E by a scale factor of
from centre of enlargement (4,8).
Label the new shape E’.
C
E
D
1
,
2
Positive & Fractional Enlargements
3) Describe these two enlargements of A to B
Enlarge shape A by a scale factor of 2,
1) from centre of enlargement (11,3).
2)
Label the new shape A’.
Enlarge shape B by a scale factor of 3,
from centre of enlargement (5,2).
Label the new shape B’.
②
Scale Factor = 2
Centre of Enlargement = (8,2)
B
A
B’
B
A’
A
A
B
Scale Factor = 3
Centre of Enlargement = (10,5)
4)
Enlarge shape C by a scale factor of
from centre of enlargement (11,4).
Label the new shape C’.
1
,
2
5)
Enlarge shape D by a scale factor of
from centre of enlargement (2,10).
Label the new shape D’.
1
,
3
6)
Enlarge shape E by a scale factor of
from centre of enlargement (4,8).
Label the new shape E’.
C
D’
E’
C’
E
Answers
D
1
,
2
KNOWLEDGE CHECK
Describe the enlargement
A to B.
B
A
Describe the enlargement
B to A.
KNOWLEDGE CHECK
Describe the enlargement
A to B.
B
A
Scale Factor = 2
Centre of Enlargement = (-5,-5)
Describe the enlargement
B to A.
1
Scale Factor =
2
Centre of Enlargement = (-5,-5)
Check your success!
I can enlarge shapes by an integer scale factor.
I can enlarge shapes by an integer scale factor
and a centre of enlargement.
I can enlarge shapes by a fractional scale factor.
Check your success!
I can enlarge shapes by an integer scale factor.
I can enlarge shapes by an integer scale factor
and a centre of enlargement.
I can enlarge shapes by a fractional scale factor.
Write a text message to a friend describing…
The ‘counting
squares’ method of
enlargement.
Questions?
Comments?
Suggestions?
…or have you found a mistake!?
Any feedback would be appreciated .
Please feel free to email:
tom@goteachmaths.co.uk