How did people first learn how to smelt metal? They probably learned through a gradual process of experimentation, observation, and learning from the results. Copper was the first metal to be smelted on a large scale, at least by around 5000 BC. The discovery of smelting is probably one of the most important discoveries of […]
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Why does starch thicken sauce? Starch thickens sauces because starch granules swell when they are heated in water. As they swell, they trap water and release long starch molecules that tangle together, turning a thin liquid into a thicker one. Starch is a complex carbohydrate that is produced by green plants as their main way
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How do insects survive the winter? A lot of insects don’t survive the winter, and they haven’t evolved to. They are born, live long enough to reproduce, lay eggs, and die. However, that does not mean the species dies out. Many insects survive winter as eggs, larvae, nymphs, or pupae. Other insects live through the
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How can some animals be transparent? Animals can be transparent if their bodies let light pass through them without absorbing, reflecting, or scattering too much of it. There are not many transparent animals, and most of them are found in water. Some of them are partially transparent and some are almost completely transparent. Even animals
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How did the Allies keep D-Day a secret? The Allies kept D-Day secret through a mixture of deception, censorship, and need-to-know security. D-Day was Tuesday, June 6th, 1944. The landings in Normandy were the beginning of the Allied return to Western Europe. The overall campaign was called Operation Overlord, and the naval invasion itself was
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How do you dismantle a skyscraper? There are several ways to dismantle a skyscraper, but none of them are easy. The method depends on where the skyscraper is located, what it is made of, how tall it is, and what is standing around it. The first skyscrapers were built in the 1880s. They were made
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Do people actually live in igloos? People don’t usually live in snow igloos permanently, but some Inuit groups historically used them as winter homes or temporary hunting shelters. The English word “igloo” comes from the Inuit word “iglu,” which means house or home. It does not necessarily mean a house made of snow. In some
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What is jerky? Jerky is traditionally strips of dried meat that are eaten as a snack or as a way to get protein and energy on long journeys where there is no access to refrigeration. The concept of jerky has been around for thousands of years, but the word has only existed in English since
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Why were spices so valuable in the past? You can buy a jar of spices today for a few dollars, but for a large part of history, some spices were extremely valuable. A few were even said to be worth their weight in gold. This was generally down to how hard they were to get,
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How does a spring work? A spring works by storing mechanical energy when it is deformed and then releasing that energy when it returns to its original shape. Springs don’t have to be metal, but in human-made springs, metal is probably the most common material. There are natural springs as well. The tendons in a
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