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Rotational Symmetry

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Title: Students Enchanted by Merlin s Spell! Author: Richard English Last modified by: admin Created Date: 10/7/2000 10:32:34 AM Document presentation format – PowerPoint PPT presentation

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Title: Rotational Symmetry


1
Rotational Symmetry
2
Rotational Symmetry
  • If, when you rotate a shape, it looks exactly the
    same as it did in its original position, then we
    say that the shape has rotational symmetry.
  • This square has rotational symmetry.
  • It looks exactly the same four times in a full
    turn.
  • It has rotational symmetry order 4.

3
Rotational Symmetry
  • Does this rectangle have rotational symmetry?

Yes, it fits!
No, it doesnt fit
No, it doesnt fit
Yes, it fits!
Click to rotate the rectangle.
  • It looks exactly the same twice in a full turn.
  • It has rotational symmetry order 2.

4
Rotational Symmetry in the Alphabet
  • Which letters have rotational symmetry?

Click to see the answers.
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
Order 2
Order 2
Order 2
Order 2
S
T
U
V
W
X
Y
Z
Order 2
Order 2
Order 2
5
Rotational Symmetry all around us
  • Which road signs have rotational symmetry?

Click to see the answers.
6
Rotational Symmetry all around us
  • Click to see the road signs with rotational
    symmetry.

Order 3
Order 2
Order 2
7
Rotational Symmetry all around us
  • Click to see more road signs with rotational
    symmetry.

Order 4
Order 3
Order 2
8
Rotational Symmetry all around us
  • Click to see more road signs with rotational
    symmetry.

Order 3
Order 2
9
Rotational Symmetry with Pentominoes
  • If you dont know what a pentomino is, then click
    here.
  • If you have done the pentominoes activity before,
    then you will know what a pentomino is and how
    many different pentominoes there are.
  • Here they are ...

10
Rotational Symmetry with Pentominoes
  • Which Pentominoes have rotational symmetry?
  • Sort them according to their rotational symmetry.

11
Rotational Symmetry with Pentominoes
Rotational Symmetry Order 2
Rotational Symmetry Order 4
Click to start sorting
12
Rotational Symmetry with 7-Pin Polygons
  • If you dont know what a 7-pin polygon is, then
    click here.
  • If you have done the 7-pin polygons activity
    before, then you will know what a 7-pin polygon
    is and how many different ones there are.
  • Here they are ...

13
Rotational Symmetry with 7-Pin Polygons
  • Which 7-Pin Polygons have rotational symmetry?
  • Sort them according to their rotational symmetry.

14
Rotational Symmetry with 7-Pin Polygons
Rotational Symmetry Order 2
Rotational Symmetry Order 6
Rotational Symmetry Order 3
Click to start sorting
15
Now you know all about rotational symmetry!END
OF PRESENTATION
16
Pentominoes
  • A pentomino is made out of five squares that are
    connected along at least one edge.

These are NOT pentominoes.
Here is an example of a pentomino.
How many different pentominoes can you find?
Click here to return to line symmetry.
17
7-Pin Polygons
  • Here is an arrangement of 7 pins.

A 7-pin polygon is a closed shape with straight
sides with corners on the pins.
Here are some examples of 7-pin polygons.
How many different 7-pin polygons can you find?
Click here to return to line symmetry.
18
END OF PRESENTATION
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