# Lesson 16

More Symmetry

### Lesson Narrative

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 warm-up as they identify different types of symmetry (MP6). Students continue using precise language in their justifications of symmetry throughout the activities.

### Learning Goals

Teacher Facing

• Describe (orally and in writing) the rotations that take a figure onto itself.

### Student Facing

Let’s describe more symmetries of shapes.

### 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.

### Student Facing

• I can describe the rotations that take a figure onto itself.

Building On

### Glossary Entries

• 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.)