10 6 symmetry lesson

1. SymmetrySymmetry
Two Types:Two Types:
1. Line Symmetry (can 1. Line Symmetry (can
be called be called reflectional reflectional
symmetrysymmetry)–)– if you if you
can fold a shape and can fold a shape and
have the edges meethave the edges meet
The place where you The place where you
fold is called the fold is called the line line
of symmetryof symmetry

2. More Line SymmetryMore Line Symmetry
reflectional symmetryreflectional symmetry

3. Line Symmetry in the AlphabetLine Symmetry in the Alphabet
Which letters have got lines of symmetry?Which letters have got lines of symmetry?
ABCDEFGHI
JKLMNOPQR
STUVWXYZ
Click to see the lines of symmetry.Click to see the lines of symmetry.

4. Lines of Symmetry all around usLines of Symmetry all around us
Which of these road signs have got lines of Which of these road signs have got lines of
symmetry?symmetry?Click to see the lines of symmetry.Click to see the lines of symmetry.

5. CarpetsCarpets

6. Examples:Examples:
Do the following shapes have line Do the following shapes have line
symmetry? If so, how many lines of symmetry? If so, how many lines of
symmetry do they have?symmetry do they have?
a. b. c. d. e. a. b. c. d. e.
1 Line1 Line 2 Lines2 Lines4 Lines4 Lines 2 Lines2 Lines
No No
LinesLines

7. Rotational SymmetryRotational Symmetry
2. Rotational Symmetry: If you can turn 2. Rotational Symmetry: If you can turn
the shape less than 360the shape less than 360
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and still have and still have
the same shape.the same shape.
Order of Rotational Symmetry: Is the Order of Rotational Symmetry: Is the
number of rotations that must be made to number of rotations that must be made to
return to the original orientationreturn to the original orientation
Minimum Rotational Symmetry: The Minimum Rotational Symmetry: The
smallest number of degrees a shape can smallest number of degrees a shape can
be rotated and fit exactly on itselfbe rotated and fit exactly on itself
Hint: Take 360Hint: Take 360
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divided by the number of divided by the number of
sides/points.sides/points.
Optional – extra information

8. SymmetrySymmetry
A figure that has A figure that has rotational symmetryrotational symmetry is its is its
own image for some rotation of 180own image for some rotation of 180° ° or or
lessless. A figure that has . A figure that has point symmetrypoint symmetry has has
180180° rotational symmetry.° rotational symmetry.
A square has 90° and 180° rotational A square has 90° and 180° rotational
symmetry with the center of rotation at the symmetry with the center of rotation at the
center of the square. A square also has center of the square. A square also has
point symmetry.point symmetry.

9. Identifying Rotational SymmetryIdentifying Rotational Symmetry
Identify any rotational symmetry in the Identify any rotational symmetry in the
figure.figure.

10. Identifying Rotational SymmetryIdentifying Rotational Symmetry
This figure has rotational symmetry, It will This figure has rotational symmetry, It will
coincide with itself after being rotated 90coincide with itself after being rotated 90° °
or 180° in either direction.or 180° in either direction.

11. Identifying Rotational SymmetryIdentifying Rotational Symmetry
This figure has rotational symmetry. It will This figure has rotational symmetry. It will
coincide with itself after being rotated 60coincide with itself after being rotated 60°°, ,
120120°°, or 180, or 180°° in either direction. in either direction.

12. Identifying Rotational SymmetryIdentifying Rotational Symmetry
This figure has no rotational symmetry. It This figure has no rotational symmetry. It
does have horizontal line of symmetry.does have horizontal line of symmetry.

13. Examples:Examples:

14. Rotational Symmetry all around Rotational Symmetry all around
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Which road signs have got rotational symmetry?Which road signs have got rotational symmetry?
Click to see the answers.Click to see the answers.

15. Rotational Symmetry all around Rotational Symmetry all around
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Which road signs have got rotational symmetry?Which road signs have got rotational symmetry?

16. Rotational Symmetry all around Rotational Symmetry all around
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Order 3 Order 2 Order 2

17. Rotational Symmetry all around Rotational Symmetry all around
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Order 4 Order 3 Order 2

18. Rotational Symmetry all around Rotational Symmetry all around
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Order 3 Order 2