My primary school teacher used to tell us riddles every Friday and then we had a week to figure them out. We were only allowed to ask her yes or no question in order to get hints to solve the riddles. I came across some silly riddles on the internet the other day which reminded me of my teacher. The best one she told us was probably this one:
I stopped in front of a hotel and at that moment I knew I was broke.
How could I know this?