NCERT Class 7 Science Curiosity: Chapter 8 — Measurement of Time and Motion
This chapter, "Measurement of Time and Motion," from NCERT's Class 7 Science Curiosity textbook, begins by exploring the historical methods of timekeeping. It introduces Prerna, a sprinter, whose amazement at modern timing devices sparks curiosity about how time was measured before clocks. The chapter details ancient devices like sundials, water clocks, hourglasses, and candle clocks, explaining how each utilized natural phenomena like the Sun's shadow, water flow, sand flow, or burning candles to mark the passage of time. It highlights humanity's long-standing interest in tracking time, driven by observing repeating natural events like day-night cycles and seasons. This foundational understanding of time measurement is crucial for comprehending motion and its scientific study in subsequent sections.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 7 |
| Subject | Science |
| Book | Curiosity |
| Chapter | Chapter 8 — Measurement of Time and Motion |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 3 minutes |
| Word count | 540 |
Learning outcomes
- Understand the historical development of time measurement.
- Identify and describe ancient timekeeping devices such as sundials, water clocks, hourglasses, and candle clocks.
- Recognize the natural cycles that early humans used for timekeeping.
- Appreciate the advancements in modern time measurement.
Vocabulary
| Word | Meaning |
|---|---|
| Stopwatch | A special kind of watch used for timing races. |
| Sundial | A device that measures time using the changing position of a shadow cast by the Sun. |
| Water clock | A device that measures time based on the flow of water. |
| Hourglass | A device that measures time based on the flow of sand from one bulb to another. |
| Candle clock | A candle with markings that indicate the passage of time when burned. |
| Intervals | Periods of time between two events. |
| Phases of the Moon | The different appearances of the Moon as seen from Earth over about a month. |
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Practice questions
- Name any two ancient devices used for measuring time. Answer: Sundials, water clocks, hourglasses, and candle clocks are ancient devices for measuring time.
- How does a sundial measure time? Answer: A sundial measures time by the changing position of the shadow of an object cast by sunlight.
- What natural events did early humans observe for timekeeping? Answer: Early humans observed the rising and setting of the Sun, the phases of the Moon, and the changing seasons.
- How does an hourglass work? Answer: An hourglass measures time based on the flow of sand from one bulb to another.
Frequently asked questions
What are some ancient methods used to measure time?
Ancient methods included sundials, water clocks, hourglasses, and candle clocks.
How did early humans initially track time?
Early humans tracked time by observing repeating natural events like the rising and setting of the Sun, Moon phases, and changing seasons.
What is a sundial based on?
A sundial is based on the changing position of a shadow cast by an object in sunlight.
Explain the working of a water clock.
Water clocks measure time using the controlled flow of water, either out of or into a vessel.
How does an hourglass measure time?
An hourglass measures time by the steady flow of sand from one glass bulb to another.
What is a candle clock?
A candle clock is a candle with markings on it, where the burning of the candle indicates the passage of time.
Related resources
Important topics
Topics covered
NCERT Class 7 Science — Curiosity — Chapter 8 — Measurement of Time and Motion. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.