What is smelting? Iron ore is a rock that contains iron and oxygen. Smelting is the process of extracting iron from iron ore. Iron ore, limestone and coke (a form of carbon) are heated together in a blast furnace while hot air is blasted in....
What is an X-ray? We take X-rays usually after we have an accident or a bad fall. It is a kind of camera that takes pictures of our internal organs. It emits invisible light rays which pass through our skin and muscles but not hard...
Why is there frost more often on clear nights than on cloudy ones? Frost forms overnight when the temperature falls below 0°C and the dew freezes. Clouds prevent the heat that has built up in the land, sea and air during the day from escaping....
How was alcohol discovered? Alcohol is an organic compound. It is a compound of carbon, hydrogen and oxygen. Grapes have natural yeast on their skins. Under warm conditions, grape juice can ferment without the addition of more yeast. This fermented grape juice had a strong...
Why do birds moult? A Birds grow new feathers in place of old ones. The process is called moulting. In the winter season, they grow a thick coat of feathers which keep them warm. During the summer these feathers fall off and new, colourful ones...
Who were gladiators? The Romans loved violent sport. They had amphitheatres to watch violent shows called ‘games’. Gladiators fought each other to the death in these amphitheatres. Sometimes they fought lions with spears, burning torches, or their bare hands.
Where did wealthy Romans live? Wealthy Romans often had two homes. One was a country home or villa and the other a town home. There was a courtyard around which houses were built and had many rooms. They also had running water, kitchens, central heating...
What is the pulse? Pulse is the pulsation of the arteries caused by the action of the heart. It can be felt at any artery which can be felt through the skin. The pulse rate indicates how fast the heart is beating and the state...
How do experts classify dinosaurs? Dinosaurs are divided into two groups based on their hip shapes. Sauropods were plant-eaters and had lizard hips. They walked on four legs. Theropods were meat-eaters and had two legs. They too had lizard hips. Bird-hipped dinosaurs which ate plants...
What is the origin of the Christmas tree? The Christmas tree is more a tradition than a religious observance. It symbolises the spirit of Yuletide in many homes. The tradition originated in Germany. In the old days, the pagans worshipped trees but Christians changed the...
