Shadow stick - The technical name for a shadow stick is gnomon, pronounced "No mon", and is Greek for "the one who knows".

Latitude is a measure of north-south position on the globe. It is described as the angle between a position on the globe and the equator. At the equator latitude is 0°, whereas at the poles it is 90° North or 90° South. On a map these are shown as horizontal hoops around the Earth.

Gnomon - The part of a sundial that casts a shadow.

Local Apparent Time - A time-keeping system in which noon is defined as the time at which the sun is at its highest point.

Mean Solar Time - The time-keeping system used in modern clocks, in which every day is exactly 24 hours long.

Equation of Time - A complex equation that compensates for the minor differences between local time and mean solar time. These differences are due to the Earth's tilt on its axis, and the fact that the Earth's orbit around the Sun isn't a perfect circle.

Water clock - For many centuries, the best technology available for keeping time was the water clock. While these clocks weren't always reliable they worked indoors, at night and on cloudy days, so in many ways they were more useful than the sundial, the only other clock in use at the time.