The distance around a two-dimensional shape.

Know that unknown side lengths can be calculated from the perimeter and known side lengths

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 rectangle has a perimeter of 30 units. What is the length of each missing side? {{  }} units.

The rectangle has a perimeter of 20 units. What is the length of each missing side? {{  }} units.

This rectangle has a perimeter of 22 units. The long side of this shape is given. What is the length of each short side? {{  }} units.

A rectangle has a perimeter of 30 units. The long side has a length of 13 units. What is the length of each short side? {{  }} units.

A rectangle has a perimeter of 30 units. The short side has a length of 1 unit. What is the length of each long side? {{  }} units.

Which of these are possible side lengths for a rectangle with a perimeter of 50 cm?

Complete the sentence. Half of 36 is {{ }}

It is impossible to give the perimeter because there are missing side lengths. 

Which calculations will give the perimeter of this rectangle?

What is the perimeter of this rectangle? {{  }} units.

Order these rectangles from shortest to longest perimeters.

This lesson will soon be taken down.

Know that unknown side lengths can be calculated from the perimeter and known side lengths

Lesson outcome