Did you know, over 2000 years ago, Eratosthenes estimated the Earth’s circumference using math. Without ever leaving Egypt, he was accurate to within 2%.
Did you know, there is a very rare condition called Anton syndrome, in which a person becomes blind but is unaware of it and will even deny it. Their brain will generate false visual images, so they continue to believe that they can see.
Did you know, the old distress signal "SOS" does not stand for "Save Our Souls" or "Save Our Ships." The letters SOS were chosen because they're the easiest Morse Code letters to remember and use: three dots, three dashes, three dots.