2D shape and pattern
Symmetry
A shape has a line of symmetry if you can fold it along a line so that one half exactly covers the other. Some shapes have more than one.
Finding lines of symmetry
Imagine placing a mirror on the shape. If one side is an exact mirror image of the other, that line is a line of symmetry. Count all the different lines that work.
Worked examples
A square
- Try mirror lines on a square.
- There are 2 through the middle of the sides and 2 through the corners.
Answer: A square has 4 lines of symmetry.
A rectangle
- Try mirror lines on a (non-square) rectangle.
- Only the horizontal and vertical middle lines work.
Answer: A rectangle has 2 lines of symmetry.
Where you see this in real life
- The two halves of a butterfly's wings.
- Symmetrical patterns in art and design.
- Many letters, like A and M, have a line of symmetry.
Key words
- Line of symmetry
- A line where one side of a shape is a mirror image of the other.
- Symmetrical
- Having one or more lines of symmetry.