Checking and securing understanding of perimeter for compound shapes

I can calculate the perimeter of compound shapes made from rectangles, triangles, parallelograms and trapeziums efficiently.

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Year 10

Higher

Checking and securing understanding of perimeter for compound shapes

I can calculate the perimeter of compound shapes made from rectangles, triangles, parallelograms and trapeziums efficiently.

Download all resources

Share activities with pupils

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Lesson details

Key learning points

Before calculating perimeter, consider the shape and check you know the required lengths.
It is not necessary to know every side length.
Sometimes you can deduce the sum of a subset of side lengths.
Identifying where you can be more efficient can make calculations simpler.

Keywords

Perimeter - The perimeter is the distance around a 2D shape.
Compound shapes - A compound shape is a shape created using two or more basic shapes.
Composite shapes - A composite shape is an alternative for a compound shape.

Common misconception

Pupils may miss an edge when calculating the perimeter.

Encourage the pupils to trace the perimeter to check that all edges have been included in the sum.

This lesson involves Pythagoras' theorem and properties of shape, so you may wish to set a homework revisiting these skills in preparation for the lesson.

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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).