The effect of enlargement on the perimeter of a shape
I can understand the effect of an enlargement on the perimeter of a shape.
The effect of enlargement on the perimeter of a shape
I can understand the effect of an enlargement on the perimeter of a shape.
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning points
- An enlargement means the object and image are similar.
- All lengths in the object have been multiplied by the scale factor.
- By the distributive law, this means the perimeter has been multiplied by the scale factor.
Keywords
Similar - Two shapes are similar if the only difference between them is their size. Their side lengths are in the same proportions.
Invariant - A property of a shape is invariant if that property has not changed after the shape is transformed.
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.
Common misconception
"I will get different linear scale factors if a measure corresponding lengths in cm vs inches."
Scale factors do not have dimensions, and aren't linked to specific units. If one length is 23 cm (9 inches), and a corresponding length is 69 cm (27 inches), then the scale factor between them is 3, regardless of whether we measured in cm or inches.
To help you plan your year 10 maths lesson on: The effect of enlargement on the perimeter of a shape, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 10 maths lesson on: The effect of enlargement on the perimeter of a shape, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
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Explore more key stage 4 maths lessons from the Similarity unit, dive into the full secondary maths curriculum, or learn more about lesson planning.
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Starter quiz
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Exit quiz
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