Find lines of symmetry in 2D shapes
I can find lines of symmetry in 2D shapes and explain the link between lines of symmetry and number of sides in regular polygons.
Find lines of symmetry in 2D shapes
I can find lines of symmetry in 2D shapes and explain the link between lines of symmetry and number of sides in regular polygons.
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Lesson details
Key learning points
- A line of symmetry splits the shape into two equal parts which are mirror images.
- Shapes are symmetrical when they look the same when a mirror is placed on the mirror line.
- Regular polygons have the same number of lines of symmetry as they have sides.
Keywords
Symmetrical - When a shape, pattern or image has one half that is the reflection of the other half, it can be described as symmetrical.
Line of symmetry - If you were to fold a shape on its line of symmetry, both halves would match exactly.
Regular polygon - A regular polygon has sides that are all equal and angles that are all equal.
Common misconception
Children may not identify lines of symmetry that are neither horizontal nor vertical.
Allow opportunities for children to handle and manipulate cut outs of shapes so that they can try to find lines of symmetry in different orientations. Encourage them to describe the position of the line of symmetry to support their understanding.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.A __________ is a quadrilateral with two pairs of adjacent sides that are equal in length.
Q2.Adjacent means ...
Q3.This kite is also a square. It has lines of symmetry.
Q4.Look at these rectangles. Which does not show a line of symmetry?
Q5.Which of these shapes has more than one line of symmetry?
Q6.Which shape has been incorrectly sorted?
Assessment exit quiz
6 Questions
Q1.A mirror line is also called the line of __________.
Q2.A square is a regular polygon. What is true for all polygons?
Q3.Match each shape shown to the number of lines of symmetry it has.
1
2
4
Q4.This shape is a regular hexagon. It has lines of symmetry.
Q5.The number of lines of symmetry in a regular polygon is __________ the number of sides it has.
Q6.Match the number of lines of symmetry to the shapes.
4 lines of symmetry
3 lines of symmetry
5 lines of symmetry
8 lines of symmetry
6 lines of symmetry