🧠 General Science Lesson

🌱 1. The Basics of Life

All living things are made of cells, which are the smallest units of life. Some organisms are made of just one cell (like bacteria), while humans and animals have billions of them.
Inside each cell, the mitochondria act as the powerhouse, producing energy. The nucleus controls all activities in the cell.

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🌍 2. The Earth and the Atmosphere

The air around us is called the atmosphere, and it’s made mostly of nitrogen (78%) and oxygen (21%).
The skin is our largest organ, protecting our body from germs and helping regulate temperature.
Our kidneys clean our blood, removing waste and extra water.

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🌞 3. The Solar System

Our solar system has eight planets. The closest planet to the Sun is Mercury, while Mars is called the Red Planet because of its iron-rich soil.
Saturn has the most moons and is famous for its beautiful rings.
Planets move around the Sun due to the force of gravity.

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🔥 4. Matter and Energy

Everything around us is made of atoms, which have a center called the nucleus. Inside the nucleus are protons and neutrons, while electrons orbit around it.

Matter can change states — solid, liquid, or gas. Sometimes, a solid changes directly into a gas — this process is called sublimation (like dry ice turning into vapor).
The energy stored in food is chemical energy; our body converts it into usable power.

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🌈 5. Light, Heat, and Sound

Light travels incredibly fast — about 300,000 kilometers per second in a vacuum.
When light passes through water droplets, it bends and reflects, creating a rainbow.
When water reaches 100°C, it boils and turns into steam.

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🌞 6. The Human Body and Health

Our brain controls everything we do. The cerebellum helps us maintain balance, while the cerebrum is responsible for thinking and memory.
When the skin is exposed to sunlight, it produces Vitamin D, which is essential for healthy bones.
Red blood cells carry oxygen through our body, while white blood cells help fight infection.

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🌋 7. The Earth and Its Energy Sources

Energy can come from many places. Renewable sources include solar, wind, and hydroelectric power — these are better for the environment because they don’t run out.
Coal, on the other hand, is a nonrenewable energy source that contributes to pollution.

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💎 8. The Physical World

The hardest natural substance on Earth is diamond — made entirely of carbon atoms tightly packed together.
Most of the visible matter in the universe is in the plasma state — found in stars like our Sun.

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🌌 9. The Universe

The universe is made mostly of hydrogen, the simplest and most abundant element. Stars burn hydrogen to produce light and heat.

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🔬 10. Changes in Matter

There are two main types of changes:

• Physical change: The matter changes form but not its chemical makeup (like ice melting).

• Chemical change: The substance becomes something new (like wood burning into ash).

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