Calculating missing side lengths from the area of composite rectilinear shapes

You can calculate a missing side length from the area of a composite rectilinear shape.

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Year 7

Calculating missing side lengths from the area of composite rectilinear shapes

You can calculate a missing side length from the area of a composite rectilinear shape.

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Share activities with pupils

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Lesson details

Key learning points

Given the area, it is possible to calculate a missing side length.
The most efficient method may depend on the features of the shape.

Keywords

Composite rectilinear shape - A composite rectilinear shape is a composite shape made from rectangles.

Common misconception

Pupils may try to combine lengths that are not parallel to a known side length.

For two sets of side lengths to be equal, one set must be parallel to the other and none of the lengths can overlap.

This lesson demonstrates why it is important to have more than one strategy for calculating the area of composite rectilinear shapes. Highlighting this to pupils helps them to understand why one method is not always enough.

Teacher tip

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).