Maths Library

Lines of Symmetry: Year 4 maths

This topic covers identifying lines of symmetry in 2D shapes and completing symmetrical figures. The worksheet practises reflecting patterns across horizontal, vertical, and diagonal mirror lines.

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What this covers

Lines of Symmetry is taught in Year 4 (age 9 to 10) as a main teaching focus. It sits in the Geometry strand.

Worked example

How many lines of symmetry does a regular pentagon have

  1. A regular polygon has equal sides and equal angles
  2. For any regular polygon, the number of lines of symmetry equals the number of sides
  3. A regular pentagon has 5 sides, so it has 5 lines of symmetry

Answer: 5

Difficulty scale

The sheet generator offers five difficulty settings for this topic.

  1. Identifying a single vertical line of symmetry in familiar shapes
  2. Finding horizontal and vertical lines of symmetry in basic 2D shapes
  3. Counting all lines of symmetry in regular polygons
  4. Finding lines of symmetry in irregular shapes and letters of the alphabet
  5. Completing shaded patterns on a square grid across diagonal mirror lines

Common mistakes

  • Assuming any line cutting a shape in half is a line of symmetry (e.g. diagonal of a non-square rectangle)
  • Missing diagonal lines of symmetry in squares

Curriculum links

Indicative matches to Australian Curriculum v9. Check wording and codes against the official document.

  • AC9M4SP03 Apply line symmetry, reflections, rotations, and translations to shapes.

Sample sheet and answers

Six questions at the level's usual difficulty. Open the editor to change, add or regenerate any of them.

Lines of Symmetry

Year 4 maths

Qs
6
Marks
18
NameDateScore / 18
1.
How many lines of symmetry does a regular pentagon have?
[3]
2.
How many lines of symmetry does a regular pentagon have?
[3]
3.
How many lines of symmetry does a equilateral triangle have?
[3]
4.
How many lines of symmetry does a regular pentagon have?
[3]
5.
How many lines of symmetry does a square have?
[3]
6.
How many lines of symmetry does a square have?
[3]

Answer key

  1. 5A regular pentagon has 5 lines of symmetry
  2. 5A regular pentagon has 5 lines of symmetry
  3. 3A equilateral triangle has 3 lines of symmetry
  4. 5A regular pentagon has 5 lines of symmetry
  5. 4A square has 4 lines of symmetry
  6. 4A square has 4 lines of symmetry