If you were to fold a shape on its line of symmetry, both halves would match exactly.

Mirror line is another term to describe the line of symmetry.

When you reflect a shape, you flip it over a mirror line or line of symmetry without turning it or changing the size.

The reflection of a shape is the mirror image of a shape.

Diagonal lines of symmetry

Maths

In this unit pupils will pupils will complete and compose symmetrical shapes from two congruent shapes and investigate lines of symmetry in 2D shapes. In the future unit pupils will explain what area is and measure using counting as a strategy. They will make different shapes with the same area and compare the area of different 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 pupils will complete and compose symmetrical shapes from two congruent shapes and investigate lines of symmetry in 2D shapes.

Properties of 2D and 3D shapes and symmetry

Match each mirror line with its correct direction.

True or false. This shape has been correctly reflected in a diagonal line of symmetry.

Here are quadrilaterals that have been reflected with one of the sides touching the line of symmetry. Name the shapes that have been made.

This shape has been reflected in a diagonal line of symmetry. The new shape is __________.

Which of these images shows a correct reflection?

Which of these images is not a correct reflection?

Before reflection, this shape was a trapezium. Now, it is a __________.

Before reflection, this shape was a right-angled triangle. Now, it is __________.

Here are triangles that have been reflected with one of the sides touching the line of symmetry. Name the shapes that have been made.

True or false. When you reflect a square that has a side that touches the mirror line, it will create a larger square.

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

Diagonal lines of symmetry

Lesson outcome

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