Before you begin
Students should have some familiarity with lines, rays, and angles. In this lesson, students will be sketching reflections of rays, so some previous experience with reflections will be helpful, but isn’t necessary. To sketch precise reflections, students will also need to know the law of reflection: that when light hits a mirror, it is reflected over a line perpendicular to the mirror at that point. This lesson isn’t about deriving this law of nature, so if students aren’t familiar with it, you may need to present it to them beforehand.