How to read the time without the help of a clock? It's not magic ... it's mathematical! The Pedagogical Side: A sundial is a clock that uses the sun's position to indicate the time. Usually a stick (gnomon) projects the shadow of the sun on a base or a flat surface. The time is indicated on the surface according to the position of the sun's shadow. This segment explains how to make a sundial by marking the position of the shadow of a stationary object (a stick) during the day and how to read the time from the position of the shadow!