There is a famous puzzle. 9 dots arranged in a square, like this
Your job is to connect all of the dots using only 4 straight lines without lifting your hand off the paper, crossing each dot only once. The only way to do it is to extend at least one of the lines beyond the perimeter of the “box”.
This solution never occurs to most people. They see a box, and their thinking is limited by that.
Click below to check out the book by Mike Vance.