This document discusses a periscope and how it allows soldiers hiding in pits to view enemy attacks during war by using two mirrors arranged at 90 degree angles. It also provides examples of common uses for different types of mirrors, such as convex mirrors allowing drivers to see behind vehicles, concave mirrors being used in shaving and flashlights, and plane mirrors for viewing faces and in kaleidoscopes. Students are instructed to complete a figure drawing the light path through a periscope and label where reflections take place, as well as to complete a table with examples of mirror uses.