Question: You have a glass of water that looks about half full. How can you tell, only using the glass of water itself, if the glass is half full or not?
The glass is a right cylinder.
Answer: Tip the glass of water until the water reaches the rim of the glass and if the water lines up perfectly with the bottom rim of the glass, it is half full.
Question: You are in a car with your friend and your car ran out of gas. You went to the gas station to go pick up some gas. You told your friend to close all the windows and don't turn the radio on. Your friend turned the radio on and the radio was the news reporting there is a murderer in town. Your friend looked up and saw the murderer. The murderer killed your friend. How is this possible?
Answer: Your car is a convertible. You didn't say to close the top roof.