# Background for Teachers

To teach this lesson, you will need an understanding of geometric transformations, specifically rotations and reflections. For example:

- Squares have both rotational (90
^{o}, 180^{o}, 270^{o}) and reflectional symmetries (vertical, horizontal, and diagonal).

Here are some helpful YouTube videos:

How to Identify and Calculate Rotational Symmetry

Here is an interactive webpage that rotates various shapes to set degrees (please note: the rotations here are counterclockwise, where the rotations in the notes and assignment are clockwise).

https://contrib.pbslearningmedia.org/WGBH/mgbh/mgbh-int-anglerota/index.html

There are also two copies of the notes and assignment. One is a student version, and the other is the teacher version which includes the answers.