Science facts for kids

Water boils at 100 °C and freezes at 0 °C (at sea level).

About 71% of the Earth’s surface is covered by water, and most of it is salty sea water.

Air is mostly nitrogen (about 78%). The oxygen we breathe is about 21%.

A rainbow has 7 colours: VIBGYOR, violet, indigo, blue, green, yellow, orange and red. Raindrops split sunlight into these colours.

A flash of lightning is hotter than the surface of the Sun.

You see lightning before you hear thunder because light is much faster than sound. Count the seconds between them and divide by 3: that is roughly how many km away the storm is.

Light travels about 3 lakh km every second.

Sound cannot travel through empty space, because there is no air to carry it.

Sound travels about four times faster in water than in air.

Magnets: opposite poles pull together, and the same poles push apart.

The “lead” in a pencil is really graphite, made of carbon, just like a diamond!

The Earth spins once a day, which gives us day and night. It goes round the Sun in about 365¼ days, so every 4 years we add a day: 29 February.

Plants make their own food from sunlight, water and air. This is called photosynthesis, and it gives out the oxygen we breathe.

Leaves are green because of chlorophyll, which catches sunlight.

Deep inside, the Earth is so hot that rock melts. When it comes out of a volcano, it is called lava.

C. V. Raman won the Nobel Prize in Physics in 1930 for the Raman effect, about how light scatters. We celebrate National Science Day on 28 February, the day he announced it in 1928.

Jagadish Chandra Bose showed that plants respond to the world around them, and built the crescograph to measure how plants grow.

Srinivasa Ramanujan was a brilliant mathematician. His birthday, 22 December, is National Mathematics Day.

Janaki Ammal was a plant scientist who helped breed sweeter sugarcane for India.

Dr A. P. J. Abdul Kalam, the “Missile Man of India”, was a rocket scientist who became President of India.