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==Key Stage 3=====Meaning===A '''scientific theory''' is a set of scientific facts linked together to [[explain]] an [[observation]]. ===About Scientific Theories===: A '''scientific theory''' should not be confused with a regular '''theory'''. '''Scientific theories''' are based on facts and have had hundreds of [[scientist]]s performing [[investigation]]s and [[experiment]]s to prove it wrong. The idea is that if they can't prove it wrong, then it's probably true. A regular '''theory''' is just a guess made by someone who hasn't performed any [[investigation]]s or [[experiment]]s.There are a number of '''scientific theories''' you may know:*The [[Germ Theory of Disease]] - The '''scientific theory''' that many [[disease]]s are caused by [[micro-organisms]].*The [[Heliocentric Theory]] - The '''scientific theory''' that the [[Sun]] is at the centre of [[The Solar System]].*[[Newton's Theory of Universal Gravitation]] - The '''scientific theory''' that the [[planet]]s are held [[orbit]]ing the [[Sun]] by the [[force]] of [[gravity]].*The Theory of [[Evolution by Natural Selection]] - That [[population]]s [[evolve]] new [[adaptation]]s over time due to the natural environment.