When did the modern census start? The modern census developed gradually between the late 17th and mid-19th centuries. Most civilizations have had some kind of census since the beginning of civilizations. It is always important to know how many people you have in your country because then you can tax them properly and you always […]
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Why do mountains form in chains? Mountains form in chains because they are produced at the point where two tectonic plates meet, but there are different ways that tectonic plates can make mountains. Mountain chains are very long, often thousands of kilometers long, because the major tectonic plates are much larger than we probably imagine.
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How did Chairman Mao take over China? Chairman Mao took over China mainly because the Long March consolidated his leadership, the Second World War weakened the Nationalists, he gained widespread rural support, and the Soviet Union supplied his forces with captured Japanese weapons. The Long March is a very famous event in China that happened
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What was the Dreyfus affair? The Dreyfus affair was a political scandal in France in 1894 that revealed the injustice and antisemitism in the French government at the time. The whole affair centered around Alfred Dreyfus, a Jewish French army officer. He was born in 1859 and joined the French army at the age of
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How does the Netherlands reclaim land from the sea? They build a dike and then pump out the water. Before we look at how they do it, I thought it would be interesting to learn why Holland is called the Netherlands. Most of you probably know this, but I didn’t. The Netherlands is the official
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What is the Roche limit? The Roche limit is the minimum distance that one planetary body can approach another planetary body without being torn to pieces. The Roche limit is named after Edouard Roche, the French astronomer who first calculated it in 1848. He came up with his theory while he was studying the rings
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Why was the Erie Canal important? The Erie Canal was important because it connected the Atlantic Ocean to the Great Lakes. This cut down shipping time and costs, and it unlocked the American Midwest. The Erie Canal is 584 km long. It runs from the Hudson River in New York State to Lake Erie. The
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When did castles stop using moats? Castles stopped using moats in the 16th century, and the whole design of castles changed to reflect new technology in warfare. If you have ever visited the ruins of an old castle, you probably noticed that you need to cross a bridge to get into it. The bridge spans
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What is a magnetar? A magnetar is a neutron star that is the size of a city but is one of the strongest magnetic objects in the universe. Many planets and stars have a magnetic field. Our Earth has a magnetic field that is produced by the spinning liquid metal in the outer core. The
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Why don’t spiders get stuck in their own webs? Spiders don’t get stuck because not all of the web is sticky, they know where to put their feet, and their feet are adapted for walking on silk. There may also be chemical help from their legs, but that part is still not completely proven. Spiders
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