ELI5: Explain Like I'm 5

Mental rotation

Mental rotation is when you use your brain to imagine how an object would look like after it has been turned or rotated in space. To do this you have to be able to imagine how one side of the object would look different if it was turned or rotated. For example, if you had a square and mentally rotated it, you would be able to picture how the four sides of the square would look different in different positions.
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