You are riding to school on a bus in a snowstorm. Through the window, you see a lighted sign that gives the temperature as 26 degrees, but you cannot make out wether the temperature scale is Celsius or Fahrenheit. Which is it, and how do you know?
It is obviously degrees Fahrenheit as water freezes at zero degrees Celcius, and 26 degrees Celcius would be way too warm for a snowstorm to occur, whereas 26 degrees Fahrenheit is way below the freezing point of water.
