Multi-Part Lesson
9-3
Symmetry
PART
Main Idea
I will identify and
describe reflections.
New Vocabulary
rotational symmetry
macmillanmh.com
A
B
C
Rotational Symmetry
You have learned that images can reflect over a line of
symmetry to show line symmetry. Images that lie in the
same position after rotating 180° or less around a point
have rotational symmetry .
A snowflake shows rotational symmetry.
Materials
construction or plain
paper
scissors
Mini-Activity
Create a design that shows rotational symmetry.
Step 1
EXP-Scissors
Fold paper.
Fold a square piece of paper into
8 equal pieces as shown.
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Cut paper.
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Keep the paper folded. Cut shapes out of the sides.
Step 3
Unfold paper.
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Unfold the paper to see the design that shows
rotational symmetry.
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Identify Rotational Symmetry
Tell whether each figure shows rotational symmetry.
Write yes or no.
The starfish will lie in the same position after rotating 180°
or less around its center.
So, the starfish has rotational symmetry.
The dragonfly does not rotate around a point.
So, the dragonfly does not have rotational symmetry.
Tell whether each figure shows rotational symmetry. Write yes
or no. See Examples 1 and 2 (p. 455)
1.
2.
4. Kelvin has a bicycle. Does each
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tire show rotational symmetry?
Explain.
5.
3.
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Describe a real-world example of
rotational symmetry.
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EXTRA
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See page R29.
Tell whether each figure shows rotational symmetry. Write yes
or no. See Examples 1 and 2 (p. 455)
6.
7.
8.
9.
10.
11.
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12. Does the leaf below show rotational
13. Does the wagon wheel
below show
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symmetry? Explain.
rotational symmetry? Explain.
14. Does the movement of the gymnast
15. Do all real-world objects that are in the
around the bar show a rotation? Explain.
shape of a circle show rotational
symmetry? Explain.
16. OPEN ENDED Draw a shape that has rotational symmetry.
17. WHICH ONE DOESN’T BELONG? Which shape does not belong
with the other three? Explain.
18.
456
Is it possible for a shape to have both line
and rotational symmetry? Explain.
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Practice
19. Rotational symmetry can be seen in
many flowers. Which flower does
NOT show rotational symmetry?
20. Terry wrote four names. Which
name shows line symmetry?
F. TIM
A.
G. KIM
H. JAN
I. BOB
B.
C.
21. Some pattern blocks show
rotational symmetry. Which pattern
block does NOT show rotational
symmetry?
A. triangle
B. trapezoid
D.
C. square
D. hexagon
Tell whether each figure has line symmetry. Write yes or no.
If yes, tell how many lines of symmetry the figure has. (Lesson 9-3B)
22.
23.
24. C09-298A-112056
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25.
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26. Chung is having a snack. What transformation does the apple
represent? Explain. (Lesson 9-2E) reflection; The line of reflection
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