1. Symmetry
       

2. Line Symmetry
Shape has line symmetry when one half of it is the mirror image of the other half.
Think of it like a fold line.
        How would you define the term 'line symmetry'?         Why might some people see line symmetry as a thing of beauty?

3. Line Symmetry
If a shape can be folded in half so that one half fits exactly on top of the other, then we say that the shape has got line symmetry.
The fold is called a line of symmetry.
This shape has got a vertical line of symmetry.

4. Is a butterfly symmetrical?

5. At the beach there are lots of shells with line symmetry.

6. Under the sea there are also many symmetrical objects.1 2
This type of symmetry is also called reflectional symmetry as the two parts reflect/match along each side of a dividing line ( or axis ). 1 3 4 5

7. Land animals often have symmetry, too.

8. Do these masks have a line of symmetry?
Yes, they do.

9. If an object is reflected in water it is considered to have line symmetry along the waterline.

10. The Taj Mahal
In this view of the building there is a line of symmetry through the centre of the tomb from top to bottom. It was completed in 1630 by the Indian ruler Shahs Jahan as a tomb for his favourite wife Mumtaz Mahal who died as a result of giving birth to their 14th child.
To build this tomb it took workers, 20 years (Encarta 97) and it is rumoured that they used elephants to transport the materials.
Symmetry exists in architecture all around the world.  One of the best known examples of this is the Taj Mahal in India.

11. This photograph shows 2 lines of symmetry. Where are they?

12. Which of these road signs have lines of symmetry?

13. Line Symmetry with Pentominoes
How many lines of symmetry does each Pentomino have?

14. Line Symmetry with Polygons
How many lines of symmetry does each polygon have?

15. Line Symmetry in the Alphabet
Which letters have got lines of symmetry? A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

16. How many lines of symmetry in an equilateral triangle?

17. an equilateral triangle has 3 angles and 3 lines of symmetry

18. How many lines of symmetry in a square?

19. a square has 4 angles and 4 lines of symmetry

20. How about a regular pentagon?

21. a regular pentagon has 5 angles and 5 lines of symmetry

22. A hexagon?

23. a regular hexagon has 6 angles and 6 lines of symmetry

24. An octagon?

25. a regular octagon has 8 angles and 8 lines of symmetry
Is there a pattern here?
            How could you prove that a square really does have 4 lines of symmetry and not 2.             A rectangle has 4 lines of symmetry. True or False? How could you prove it?             What pattern can you see emerging on this page?

26. Did you see a pattern there?
What is your prediction for this regular decagon?
Yes! It’s 10.