Lesson 5: 3-5: Symmetry

1. What common geometric shapes always have at least one line of symmetry?
2. How can you use tools to check that a figure has line symmetry?
3. What common geometric shapes always have rotational symmetry?
4. If you know the order of symmetry, how can you find the magnitude of symmetry?
5. If you know the magnitude of symmetry, how can you find the order of symmetry?

Symmetry
Line Symmetry
Line of Symmetry
Rotational Symmetry
Center of Symmetry
Order of Symmetry
Magnitude of Symmetry

G.CO.3
Given a rectangle, parallelogram trapezoid, or regular polygon, describe the rotations and reflections that carry it onto itself.

A figure has symmetry if there is a rigid transformation that maps the figure onto itself. A figure has line symmetry if it can be mapped onto itself by a reflection and rotational symmetry if it can be mapped onto itself by a rotation.

In the animal kingdom, the symmetry of an animal's body is often an indication of the animal's complexity. Animals displaying line symmetry, such as insects, are usually more complex life forms than those displaying rotational symmetry, like a jellyfish.

Students approaching grade level can be given practice problems in small groups to work with other students or directly with the teacher.
Students beyond grade level can make deeper connections in the following way: working together to come up with examples of objects in nature that have symmetry and determine if the examples have line symmetry, rotational symmetry, or both.

Formative Assessment

Textbook in class

Access online textbook and resources through class link.