Solve problems involving the perimeter and side lengths of polygons

Maths

Know that a regular polygon has sides that are the same length and angles that are the same size

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

Understand that different shapes can have the same perimeter

Know that perimeter is measured in units of length and can be found by counting or measuring units

Know that perimeter can be calculated by adding together the side lengths of a 2D shape

Know that the perimeter of a rectangle can be calculated by addition and multiplication

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

Understand that the perimeter of a regular polygon can be calculated by multiplication

Calculate the side length of a regular polygon by division where the perimeter is known

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.

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

A regular triangle and a square have the same perimeter, which is a whole number. What could the perimeters be?

A regular triangle and a square each have a perimeter of 12 cm. What is the side length of each shape?

Shape A is a square with a perimeter of 16 cm. A new shape has been composed from copies of shape A. What is its perimeter? {{  }} cm.

Shape A is a square with a perimeter of 12 cm. A new shape has been composed from copies of shape A. What is its perimeter? {{  }} cm.

Shape A is a regular hexagon with a perimeter of 30 cm. A new shape has been composed from copies of shape A. What is its perimeter? {{  }} cm.

Continue the sequence:
3, 6, 9, 12, {{  }}

Which of these numbers would you say if you were counting in fours from zero?

Match the number of sides to the shape name.

What is the side length of a square with a perimeter of 20 cm? 

What is the side length of a regular triangle with a perimeter of 30 cm? {{  }} cm

What is the side length of a regular five-sided polygon with a perimeter of 25 cm? {{  }} cm.

Solve problems involving the perimeter and side lengths of polygons

Lesson outcome