Lesson 16: More Symmetry
About this lesson
In this lesson, students continue to examine cases in which applying a certain rigid motion to a shape doesn’t change it, and this time, students will be looking at rotation symmetry. For a shape to have rotation symmetry, there must be an angle for which the rotation takes the shape to itself. Students have opportunities to use precise language in the warmup as they identify different types of symmetry (MP6). Students continue using precise language in their justifications of symmetry throughout the activities.
Lesson overview
 16.1 Warmup: Which One Doesn't Belong: Symmetry (5 minutes)

16.2 Activity: Self Rotation (20 minutes)
 Includes "Are you Ready for More?" extension problem
 16.3 Activity: Parallelogram Symmetry (10 minutes)
 Lesson Synthesis
 16.4 Cooldown: Mystery Quad (5 minutes)
Learning goals:
 Describe (orally and in writing) the rotations that take a figure onto itself.
Learning goals (student facing):
 Let’s describe more symmetries of shapes.
Learning targets (student facing):
 I can describe the rotations that take a figure onto itself.
Required materials:
 Copies of blackline master
 Geometry toolkits
 Sticky notes
 Tools for creating a visual display
Required preparation:
 If there are not enough leftover shapes from the previous lesson, prepare more copies of the blackline master from Self Reflection so that each student in each group gets copies of the shape their group will investigate in Self Rotation.
Glossary:

rotation symmetry  A figure has rotation symmetry if there is a rotation that takes the figure onto itself. (We don't count rotations using angles such as \(0^\circ\) and \(360^\circ\) that leave every point on the figure where it is.)
 Access the complete Geometry Course glossary.
Standards:
 This lesson builds on the standards:CCSS.HSGCO.A.1MS.GCO.1MO.G.CO.A.1CCSS.HSGCO.A.4MS.GCO.4MO.G.CO.A.4
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