sundial

Everyday

An old instrument that shows the time of day by the shadow that a pointer (the gnomon) casts on a flat dial marked with hours. tree →

In the lessons

In science and history lessons a sundial shows how the Sun seems to move across the sky; as the Earth turns, the shadow moves round the dial. It only works when the Sun shines. Pupils make their own with a stick and chalk marks.

Examples

• The sundial in the garden shows it is about three o'clock. tree →
• A sundial does not work at night or on cloudy days. tree →
• We made a sundial with a pencil and a paper plate. tree →
• The shadow on the sundial moves as the Earth turns. tree →
• Old churches often have sundials on their walls. tree →
• The shadow is shortest at noon, when the Sun is highest. tree →

Note

One word: sun + dial. The shadow moves «clockwise» in the northern hemisphere (that is where clockwise comes from) and the other way in the southern hemisphere. Sundial time can differ from clock time.