In this lesson, students will investigate the relationship between an object and its image in a plane mirror. Understanding how plane mirrors work provides a useful scaffold for understanding more complex situations, such as those involving concave and convex mirrors.

• Students will observe how objects produce images in a mirror.
• Students will explore the relationship between the distance of the object from a mirror and the image distance from the mirror.
• Students will explain what an observer sees when looking at objects in a mirror.

• angle of incidence
• image
• light path
• object
• plane mirror
• reflection

This lesson has students reflect objects over a mirror line to determine the position of the image.
As a result, students will:

• Develop the understanding that the image appears the same distance behind the mirror as the object is in front of the mirror.
• Be able to explain the relationship between the observer's position and the image of an object in the mirror.