Oh god, don't get me started. In third grade my school announced that they were no longer going to teach the imperial system, and go all metric (yes this was in the USA). Being that young we couldn't care less about it because we really didn't know better. So all through grade school we were all happy using meters, liters, Celsius, etc. (actually we used Fahrenheit quite a bit also).
The schools even enlisted parents to try to use the metric system as much as possible at home. Some parents balked, but most went along with it.
Then my family moved to another state. OMFG I was so screwed as with how many teaspoons In tablespoon, or pints, quarts, gallons, inches, feet, yards, miles. It drove me nuts, but eventually I got used to it (except I still hate inches, feet, yards, miles with a passion).
I just bought a mill and a lathe. Stupid me I didn't pay attention that it was in imperial, so now I have to get the calculator out to convert back and forth. But I think I'll just break down and buy the metric conversion kit.