Count only matching folds
A square has more than one line of symmetry.
lines of symmetry
lines of symmetry
Only count lines that make matching halves.
Year 4
Identify lines of symmetry in 2-D shapes presented in different orientations
Find lines of symmetry in familiar 2-D shapes even when the shape is turned.
Lesson overview
Geometry - properties of shape
A line of symmetry splits a shape into two matching halves. The shape can still have the same symmetry when it is turned.
Turning does not change symmetry
A turned shape still keeps the same symmetry.
turned or notstill symmetric
check carefullynot all triangles match
Ignore the page direction.
Some shapes have no symmetry
Not every shape has a line of symmetry.
possible
possible
possible
Test whether both halves would match.
Worked example
How many lines of symmetry does a rectangle have?
- A rectangle folds in half vertically.
- It also folds in half horizontally.
- The diagonals do not make matching halves in an ordinary rectangle.
- So a rectangle has 2 lines of symmetry.
Round 1: Learn it
Decide whether the shape can fold onto itself and count the matching lines.
Finish this round to unlock Round 2: Show you know it.
Question 1
Which shape has 4 lines of symmetry?
4 symmetry lines
Question 2
How many lines of symmetry does a rectangle have?
count matching folds
Question 3
Which reminder is correct?
Question 4
Which shape has 2 lines of symmetry?
Question 5
What must be true for a line to be a line of symmetry?
Common mistakes
Watch for these as you work through the lesson.
- Counting lines that do not make matching halves.
- Thinking a turned shape loses its symmetry.
- Assuming every shape has a line of symmetry.
Related topics
These ideas connect closely to this lesson.
- Compare and classify geometric shapes, including quadrilaterals and triangles, based on their properties and sizes.
- Complete a simple symmetric figure with respect to a specific line of symmetry.