Earth, Moon, and the Sun
Class 7 · Science
4 ideas in Class 7 Science, explained in plain words, with games and quizzes to practise.
Rotation of the Earth and the Day-Night Cycle
Part of: Motions of the Earth and Eclipses
The Earth spins around an imaginary line called its axis once every 24 hours. Because it spins from West to East, the Sun and stars seem to rise in the East and set in the West.
Why it matters. Understanding rotation explains why we have morning, noon, and night, and why sunrise happens earlier in eastern regions.
Try it in two minutes
- Hold a torch pointing at a slowly turning ball in a dark room.
- Observe how only half the ball is lit at any moment while the other half stays in shadow.
- Show how a spot on the ball moves from darkness into light (sunrise) and back into darkness (sunset).
Try at home. Look at the night sky at 8 pm and again at 10 pm to observe how constellations appear to move around the Pole Star.
Revolution of the Earth and Changing Night Sky
Part of: Motions of the Earth and Eclipses
Revolution is the movement of the Earth along its orbit around the Sun, taking about 365 days and 6 hours. As Earth travels along this orbit, we face different parts of outer space at night.
Why it matters. Understanding revolution explains why the calendar year has 365 days and why different stars and constellations appear in different seasons.
Try it in two minutes
- Place a lamp on a table to represent the Sun and walk around it in a wide circle.
- Notice how the room walls behind the lamp change as you move to different positions in your orbit.
- Explain that our view of outer space changes across months in the same way.
Try at home. Note down the position of a prominent constellation at 8 pm this week and compare it at the same time next month.
Seasons and the Tilted Axis
Part of: Motions of the Earth and Eclipses
The Earth's axis of rotation is tilted rather than upright. As it orbits the Sun, whichever hemisphere is tilted towards the Sun receives more direct sunlight and longer daytime, causing summer.
Why it matters. Understanding the tilt corrects the common misconception that seasons are caused by Earth moving closer to or farther from the Sun.
Try it in two minutes
- Hold a globe tilted at an angle and shine a flashlight straight at it.
- Notice how light concentrates in a smaller area on the tilted-forward half and spreads thinner on the opposite half.
- Rotate the globe without changing the tilt direction and see day length differences.
Try at home. Track the sunrise and sunset times from a newspaper over three months to see how day lengths gradually change.
Solar and Lunar Eclipses
Part of: Motions of the Earth and Eclipses
A solar eclipse occurs when the Moon passes between the Sun and Earth, casting a shadow on Earth. A lunar eclipse happens when Earth passes between the Sun and the Moon, casting a shadow on the full Moon.
Why it matters. Learning about eclipses dispels ancient superstitions, explains why safe viewing techniques are vital for solar eclipses, and showcases orbital geometry.
Try it in two minutes
- Close one eye and use your small thumb to cover a large distant wall picture, demonstrating apparent size.
- Arrange a torch (Sun), a small ball (Moon), and an orange (Earth) in a straight line to show shadow casting.
- Discuss why looking directly at the Sun damages eyes, but watching an eclipsed Moon is completely safe.
Try at home. Check an astronomical calendar or sky app for the dates of upcoming eclipses visible in your region.
What your child will practise
- Revolution of the Earth and Changing Night Sky: Desert Quick Fire (Quick Fire)
- Rotation of the Earth and the Day-Night Cycle: Lab Explorer Sort (Sort It Out)
- Rotation of the Earth and the Day-Night Cycle: Space Quick Fire (Quick Fire)
- Seasons and the Tilted Axis: Desert Puzzle (Clue Puzzle)
- Solar and Lunar Eclipses: Mission Control Quest (Collect the Answer)
- Quiz: Revolution of the Earth and Changing Night Sky (8 questions)
- Quiz: Rotation of the Earth and the Day-Night Cycle (8 questions)
- Quiz: Seasons and the Tilted Axis (8 questions)
- Quiz: Solar and Lunar Eclipses (8 questions)