Comprehensive Science notes for Grade 4 students of Pakistan School, Kingdom of Bahrain. This collection covers Unit 3: Changing Sounds and Unit 4: Earth, Sun and Moon in detail, including short and long questions, definitions, true/false exercises, fill-in-the-blanks, and tiered activities.
Unit 3 – Changing Sounds
Lesson 1 – Sounds Around Us
Definition: Sound is a type of energy made by vibrations. It is anything that can be heard. How sounds are produced: By vibrations. Vibrations: Fast back-and-forth movements that create sound waves.
How sounds travel: Sounds move in invisible waves that need a medium (solid, liquid, or gas) to travel through. Sound cannot travel in empty space. It spreads in all directions from its source.
Application examples:
- Banging a door creates vibrations that produce sound waves.
- Running fingernails along a comb makes the teeth vibrate, creating sound.
Tiered Activity – Sounds Around Us
- Fill in the blanks: Sound is a form of energy; it is created when an object vibrates; loud and unpleasant sounds are called noise.
- True/False: Sound travels in all directions (T); You can hear in space (F); Sound is what we hear with our ears (T).
- Thinking question: If we could not hear, we would not sense danger or communication.
Lesson 2 – How Sounds Travel
- Sound travels fastest in solids because particles are closely packed.
- Sound takes about three seconds to travel one kilometer through air.
- In space, there is no air, so astronauts use radio waves to communicate.
- Danger sounds include horns, sirens, alarms, and buzzers.
Conversion to radio waves: Sound is converted to electrical signals through a microphone and transmitted as radio waves.
Lesson 3 – How Can We Speak and Hear?
- We speak using the voice box located in the throat.
- The human ear has three parts: outer, middle, and inner ear.
- Fish sense vibrations with special cells along their body.
- Vocal cords vibrate when air passes through, creating sound.
How hearing works: Vibrations enter the ear canal, move the eardrum, and tiny bones transfer them to the inner ear, where signals reach the brain.
Lesson 4 – Differences in Sound
- Pitch: How high or low a sound is. Fast vibrations produce high pitch; slow ones make low pitch.
- Echo: A reflected sound heard after hitting a hard surface (e.g., shouting near a mountain).
- Loud vs. Soft Sounds: Hammer sound = loud; whispering = soft.
Unit 4 – Earth, Sun, and Moon
Lesson 1 – Beyond the Earth
- The Sun is a huge ball of burning gases, 150 million km away, and 5 billion years old.
- Light from the Sun takes 8 minutes to reach Earth.
- Plants release oxygen while making food (photosynthesis).
- Inside the Sun: nuclear reactions produce heat and light.
Lesson 2 – The Solar System
- Difference between stars and planets: Stars emit light; planets reflect it.
- Asteroids: Rocky metallic bodies in space.
- Meteors: Small fragments from asteroids.
- Comets: Made of rocks, ice, and frozen gases.
Activity: Identify and label planets; recognize that only Earth supports life because of water and oxygen.
Lesson 3 – Planet Earth
- Axis: An imaginary line around which Earth rotates.
- Blue Sky: Air scatters blue light most strongly.
- Shadows: Long in morning/evening, shortest at noon.
Lesson 4 – The Changing Seasons
- Leap Year: Occurs every four years when February gains one extra day.
- Seasons: Caused by Earth’s tilt as it revolves around the Sun.
- Spring and Autumn: Occur when both hemispheres receive equal sunlight.
Activity: Label Earth’s position relative to the Sun; identify true/false statements about sunlight and shadows.
Lab Activities
- Producing Sound: Rubber bands on a box produce vibration sounds when plucked.
- Pitch in Sounds: Bottles with less water produce higher pitch; more water produces lower pitch.
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Science Notes – Grade 4 – 2025 – Pakistan School Bahrain (PDF)
Grade 4 Science Notes 2025, Pakistan School Bahrain, Changing Sounds, Earth Sun and Moon, how sound travels, pitch and echo, solar system, leap year explanation, scientific experiments, worksheets.
