Line and Rotational Symmetry

Line and Rotational Symmetry

Geometry

Symmetry

• When an object is exactly the same as another object even if it is moved, rotated or flipped.

• Lots of real-world examples.

• "Fold" the object in half and have it perfectly overlap. (oddly-satisfying!)

Poll

Symmetric?

• Yes

• No

Poll

Symmetric?

• Yes

• No

Poll

Symmetric?

• Yes

• No

Lines of Symmetry

Cutting an object in half with a line so that it creates symmetric parts. (Folded perfectly)

Multiple Choice

How many lines of symmetry does this shape have?

• 1
• 2
• 3
• 4

Multiple Choice

Determine the number of lines of symmetry for the figure.

• 0

• 1

• 3

• 6

Multiple Choice

How many lines of symmetry does the butterfly have?

• 1
• 2
• 3
• 4

Rotational Symmetry

• When you rotate an object and it looks exactly the same.

• Order of rotation: the number of times a object looks the same as it is being rotated 360 degrees (in a circle).

• Magnitude of rotation: the angle of rotation in which the object looks the same as it goes around in a circle.

Multiple Choice

What is the order of rotation in the recycling symbol?

• 1
• 2
• 3
• 1,000

Multiple Choice

Determine the angle of rotational symmetry (magnitude) for the figure.

• None

• 60°

• 120°

• 180°

Multiple Choice

What is the order and angle of rotation (magnitude) of the flag?

• Order 2, 180 degrees

• Order 4, 90 degrees

• Order 3, 120 degrees

• Order 1, 360 degrees

Success Criteria Check

• S.C.: Find the line and rotational symmetry of an object.

Multiple Choice

Determine whether the figure has line symmetry, rotational symmetry, both, or neither.

• Rotational

• Line

• Both

• Neither

Open Ended

Is there line symmetry, rotational symmetry, or both?