Starter quiz
- Enlargement is a transformation that causes a change of __________.
- 'size' ✓
- Two shapes are similar if the only difference between them is
- their angles
- one side
- one angle
- their size ✓
-
- Enlarging a shape means the shape will always get smaller.
- True
- False ✓
- Which properties are not invariant when a shape is enlarged?
- side lengths ✓
- angles
- position ✓
-
- Sam is going to triple the size of a rectangle. What will happen to the angles?
- They will all triple in size.
- They will all stay the same size. ✓
- They will all become a third of the size.
-
- Lucas' rectangle has a length of 7 cm and a width of 2.6 cm. A similar rectangle has a length of 28 cm. What will its width be?
- 1.3 cm
- 2.6 cm
- 10.4 cm ✓
- 20.8 cm
-
Exit quiz
- __________ factor is the multiplier between similar shapes that describes how large the image is compared to the object.
- 'Scale' ✓
- The ______ of enlargement is the point from which a shape is enlarged.
- 'centre' ✓
The object has been enlarged to create the image. What is the scale factor?- 3
- 4
- 5 ✓
- 6
- 20
-
- The object has been enlarged to create the image. What is the value of ?
- 3
- 12
- 15 ✓
- 20
-
The object has been enlarged to create the image. What is the scale factor?- ✓
- 5
- 5.5
- 10
-
- The object has been enlarged to create the image. What is the value of ?
- 3.2 ✓
- 5.5
- 9
- 320
-
Worksheet
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Presentation
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Lesson Details
Key learning points
- The scale factor is the multiplier.
- The centre of enlargement defines where the image will be placed in relation to the object.
- The object and enlarged image have the same orientation for positive scale factors.
Common misconception
Pupils may want to use division instead of fractional scale factors.
Dividing by 2 gives the same result as multiplying by a half. However, the scale factor is defined as a multiplier, not a divisor.
Keywords
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.
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