Checking understanding of similarity
I can enlarge a shape and can state what changes and what is invariant.
Checking understanding of similarity
I can enlarge a shape and can state what changes and what is invariant.
Lesson details
Key learning points
- An enlargement means a change in size.
- The lengths of the lines may change when enlarged.
- The angles inside an object do not change when enlarged.
- When an object is enlarged, the image is similar.
Common misconception
When a pair of similar shapes are not in the same orientation, pupils may select an incorrect pair of lengths to calculate the scale factor.
Encourage pupils to take a systematic approach to locating pairs of corresponding lengths by looking for the longest edge in each shape, then the second longest, third longest, etc.
Keywords
Object - The object is the starting figure before a transformation has been applied.
Image - The image is the resulting figure after a transformation has been applied.
Similar - Two shapes are similar if the only difference between them is their size. Their side lengths are in the same proportions.
Scale factor - Scale factor is the multiplier between similar shapes that describes how large one shape is compared to the other.
Invariant - A property of a shape is invariant if that property has not changed after the shape is transformed.
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).
Video
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Starter quiz
6 Questions
$$a\text{ }$$ cm -
6 cm
$$b\text{ }$$ cm -
8 cm
$$c\text{ }$$ cm -
10 cm
Exit quiz
6 Questions
