How Do Sundials Work?

Description:  The simplest sundial consists of two parts: a flat plate and a gnomon (or stick) that casts a shadow on the plate. When the sundial is properly aligned it will tell the local solar time. This may have to be adjusted to find national clock time due to longitude, season, and daylight savings time. Students can build their own sundial by tracing the shadow on paper (or in the dirt) at different times of the day.

Web Resources:  Sundials - Wikipedia, How Do Sundials Work? - Yale Scientific