The effect of enlargement on the area of a shape
I can understand the effect of an enlargement on the area of a shape.
The effect of enlargement on the area of a shape
I can understand the effect of an enlargement on the area 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.
- Using index laws, this means the area has been multiplied by the scale factor squared.
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
If the length of an image is 4 times as long as its object, then its area will also be 4 times as big.
If the scale factor between lengths is 4, then the area of the image will be 16 times as big. The scale factor between the length of an object and image is different to the multiplier that shows how the area of an object changes after enlargement.
To help you plan your year 10 maths lesson on: The effect of enlargement on the area 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 area 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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The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 4 maths lessons from the Similarity unit, dive into the full secondary maths curriculum, or learn more about lesson planning.
Licence
Starter quiz
6 Questions


Exit quiz
6 Questions



Linear scale factor: $$3$$ -
Area scale factor: $$9$$
Linear scale factor: $$\frac{1}{2}$$ -
Area scale factor: $$\frac{1}{4}$$
Linear scale factor: $$2$$ -
Area scale factor: $$4$$
Linear scale factor: $$4$$ -
Area scale factor: $$16$$
Linear scale factor: $$\frac{3}{2}$$ -
Area scale factor: $$\frac{9}{4}$$
Linear scale factor: $$\frac{2}{3}$$ -
Area scale factor: $$\frac{4}{9}$$
