Temperature
Converting Between Celcius and Farenheit
This isn't rocket science, but it's still pretty confusing when you're watching a soccer game or the Olympics and they're talking about it being hot because it's 30 degrees outside but you're like 30 is really cold not hot but then that's when you realize that they're probably in Europe so it's Celsius so that probably is pretty hot, like the man said, even though you're not sure of the conversion factor. Yeah, it's like that.
Kelvin Scale & Absolute Zero
Absolute zero. Not only is it super-cold, it spawned a whole new temperature scale -- with no negative temps -- and a whole new way to lose points on chemistry and math problems -- using Celsius rather than Kelvin! Wow, way to go absolute zero.