Know that the perimeter is the distance around a 2D shape

Maths

In this unit pupil will learn perimeter as the distance around the edge of a 2D shape. They will learn perimeter is measured in units of length found by counting units and by calculating by adding the side lengths of a 2D shape. In the future unit pupils will pupils will complete and compose symmetrical shapes from two congruent shapes and investigate lines of symmetry in 2D shapes. 

In the prior unit pupils investigated ways to compose and decompose polygons. They investigated quadrilaterals with and without parallel and perpendicular sides. In this unit pupil will learn perimeter as the distance around the edge of a 2D shape. They will learn perimeter is measured in units of length found by counting units and by calculating by adding the side lengths of a 2D shape.

Perimeter

The distance around the outside of a 2D shape. 

Which of these is the definition of perimeter? 

It does not matter if you go inside or outside the lines when finding perimeter.

You can start at any point in a shape, but you must finish at the same point.

You must cover the whole of the outside of the shape. 

It does not matter if you go clockwise or anti-clockwise when finding perimeter.

Which of these shows the perimeter of the triangle? 

The perimeter of Shape A is greater than Shape B.

The perimeter of Shape A is less than Shape B.   

The perimeter of Shape B is less than Shape A. 

The perimeter of Shape B is greater than Shape A.

In terms of perimeter, which of the statements are true of this image? 

The perimeter of Shape A is less than Shape B.    

The perimeter of Shape B is le less than Shape A.   

The perimeter of Shape B is greater than Shape A.  

Order the shapes according to their perimeter, starting with the shortest perimeter.

Which of these shapes has string around its outline? 

Which of these symbols means ‘greater than’?

Is this a 2D shape? Select the best answer and reason.

Number rods have been used to make polygons. Which ones are polygons?

Which 2D shapes can you see on this football pitch?

This lesson will be removed by end of Summer Term 2025.

Know that the perimeter is the distance around a 2D shape

Lesson outcome

This lesson will be removed by end of Summer Term 2025.