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Day 3:
Rotations
Objectives:
Students will be able to define rotation about a point
Students will be able to define rotational symmetry
Students will be able to apply the properties of rotation
Students will be able to relate rotations and rotational symmetry
Materials:
None
Activity:
Teacher goes over answers to homework (5 Min)
Students ask questions about problems they had trouble with
Teacher defines terms and theorems, while giving examples (15 Min)
Rotation: A rotation about a point O through x degrees is a transformation
that maps every point P to a point P', so that the following properties
are true: 1. If P is not point O, then PO = P'O and M<POP' = x
degrees. 2. If P is point ), then P = P'
Examples:
Theorem 7.2: A rotation is an isometry
Theorem 7.3: IF two lines, l and m, intersect at point O, then a reflection in l
followed by a reflection in m is a rotation about point O. The angle of
rotation is 2x, where x is the measure of the acute or right angle between
l and m.
Example:
Step 1
Step 2
Step 3
Rotational Symmetry: A figure in the plane has rotational symmetry if the
figure can be mapped onto itself by a rotation of 180 degrees or less.
Example:
Practice as a class (10 Min)
p. 341 (1-10)
Closing (5 Min)
Assessment:
Informal
Listen to answers and questions during practice
Listen to questions during lecture on definitions and theorems
Formal
Qu-est at the end of the chapter (Quiz/Test)