Lesson 9 of 16
Clocks before electricity
Show on a big screenLong ago, nobody had a wrist watch. How did people know the time?
Step 1 of 4
- A sundial. A shadow moves round as the Sun seems to move.
- A water clock. A jar drains past marks, or a bowl slowly fills.
- An hourglass. Grains fall through a narrow neck.
- A candle clock. The marks show how far it has burned.
People used a shadow, flowing water, falling sand or a burning candle.
The new words
- Sundial — a stick whose shadow shows the time of day.
- Hourglass — two glass bulbs joined by a narrow neck.
The rule
A uses a moving shadow, so it needs sunlight. A water clock uses flowing water. An uses falling sand. A candle clock uses a burning candle.
The Samrat Yantra in Jaipur is a huge , 27 m high.
On a , the shadow is long in the morning. It is shortest at noon. It is long again in the evening. The hour mark under the shadow shows the time.
Now try it. Slide the Sun. Read the time from the shadow. Then put a cloud over the Sun.
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Try the lab to finish this lesson.