Also slight off-topic, but being an American I had to grow up with the standard measures and convert late in life to metric primarily because of occupation. Doing anything with animals, particularly reptiles and amphibians means you have to think and express your self in metrics - cm, mm, grams, kgs, meters, etc. I still find, particularly with weight that I have to make a mental conversion to pounds, however at this point I'm pretty good at thinking distance in metrics. You have to slowly train your mind, but it's still weird.