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Day and Night The Earth’s Rotation and Revolution Seasons and Earth’s Tilt Day Length at Different Times of Year
Year 8 • Physics
Day and Night, Seasons & Earth’s Motion
This lesson explains why we have day and night, how Earth rotates and revolves, why seasons occur due to Earth’s tilt, and why day length changes during the year — using real-life observations to build curiosity.
Lesson Objectives
- Explain day and night using Earth’s rotation.
- Distinguish between rotation and revolution.
- Understand how Earth’s tilt causes seasons.
- Explain why day length changes during the year.
- Relate these ideas to real-life observations.
1. Day and Night
Day and night occur because the Earth rotates on its axis.
At any time, only half of the Earth faces the Sun.
[ Image Placeholder – Earth Showing Day and Night ]
• The side facing the Sun has day
• The side facing away has night
• The side facing away has night
Real-life curiosity:
When it is morning in India, it is night in parts of America.
2. Earth’s Rotation
Rotation is the spinning of Earth on its own axis.
Key facts:
• One rotation takes about 24 hours
• Causes day and night
• Earth rotates from west to east
• One rotation takes about 24 hours
• Causes day and night
• Earth rotates from west to east
Curiosity:
Sun appears to rise in the east and set in the west because of Earth’s rotation.
3. Earth’s Revolution
Revolution is the movement of Earth around the Sun.
[ Image Placeholder – Earth’s Orbit Around the Sun ]
• One revolution takes 365 days
• Causes a year
• Combined with tilt, causes seasons
• Causes a year
• Combined with tilt, causes seasons
4. Seasons and Earth’s Tilt
Earth is tilted at about 23.5°.
This tilt causes different parts of Earth to receive different amounts of sunlight.
[ Image Placeholder – Earth’s Tilt and Seasons ]
• Tilted towards Sun → Summer
• Tilted away from Sun → Winter
• Spring and autumn occur in between
• Tilted away from Sun → Winter
• Spring and autumn occur in between
Important note:
Seasons are not caused by distance from the Sun.
5. Day Length at Different Times of Year
The length of day changes during the year because of Earth’s tilt.
[ Image Placeholder – Day Length Variation Diagram ]
• Summer: longer days, shorter nights
• Winter: shorter days, longer nights
• At poles: 24-hour day or night
• Winter: shorter days, longer nights
• At poles: 24-hour day or night
Curiosity:
In summer, the Sun sets late; in winter, it sets early.
Practice Questions
A. Fill in the Blanks
- Day and night are caused by Earth’s __________.
- One rotation of Earth takes __________ hours.
- Earth takes __________ days to orbit the Sun.
- Earth is tilted at about __________ degrees.
- Longer days occur during __________.
B. True or False
- Earth rotates and revolves.
- Seasons are caused by distance from the Sun.
- Earth’s tilt causes seasons.
- Winter has longer days than summer.
- At the poles, day length can be 24 hours.
C. Short Answer
- What causes day and night?
- Define rotation.
- Define revolution.
- Why does summer have longer days?
- What causes seasons?
D. Thinking Questions
- Why do sunrise and sunset times change?
- Why is it summer in one hemisphere and winter in the other?
- Why don’t we feel Earth rotating?
- Why do polar regions have extreme day lengths?
- Why is Earth’s tilt important for life?
✅ Show Answer Key
A. Fill in the Blanks
- rotation
- 24
- 365
- 23.5
- summer
B. True or False
- True
- False
- True
- False
- True
C. Short Answer
- Earth’s rotation.
- Spinning of Earth on its axis.
- Movement of Earth around the Sun.
- Because the tilted Earth receives more sunlight.
- Earth’s tilt and revolution.
D. Thinking Questions
- Because Earth’s tilt changes sunlight angle.
- Because hemispheres tilt differently.
- Because Earth rotates smoothly.
- Because of Earth’s tilt.
- It creates seasons and climate balance.
© Aviate Learning – Day and Night & Seasons (Year 8)
🌍 Interactive Day–Night Globe Simulator
Rotate the Earth to see how day and night occur.
The bright side faces the Sun (day) and the dark side faces away (night).
Half of Earth faces the Sun (day) while the other half is in darkness (night).