Remember me to your family

I do agree that we should include some of the alternative meanings. Much of what I do is focused on alternative expressions or usage of words that the textbook does not cover.

However, as for the teaching of "-isms" and the multitudes of meanings, one still shouldn't attempt to teach too much to a middle school student since that will just confuse him/her even more. This is true for middle school students of below-average level, particularly those living in small towns where they don't have as much exposure to English as they otherwise would in the larger cities. For lower-level students, the things that should be taught (as my co-teacher wisely pointed out to me when one of my lessons nearly fell flat) first are common usages of words and phrases. The arcane subtelties of English (whether it be Americanisms, Britishisms, etc.) should only be taught to those that are truly motivated and seriously invested or if students have a competent grasp of the basic concepts and constructions.

For those in a situation where the vast majority of the students have barely any real interest in learning English, our duties is to put the carrot before the horse, not the wagon.

I don't know about the curriculum in your part of the country, but where I'm at, I'm told that the curriculum is focused on American English only.

Ask your Korean co-teachers and they will tell you that there is an overwhelming emphasis on American English in Korea, from pronunciation to spelling. I am not sure but I would suspect that this has been the case at least since the end of the Korean War.

Or, take a look at job offers in Korea and you will see that some of them are for 'North American speakers' while non specifically ask for only British, Irish, Australian, or New Zealand speakers. This, if course, is for obviously reasons.  

No, its not what you think. It is simply that America has the biggest economy, which South Korea's export economy is completely and utterly dependent upon.  

I didn't see the above post when I responded earlier. So I'll respond again.

I've been in Korea and the Korean system is centered around American English, ask any university student, English teacher or just search the textbook for the spelling of traveller and you won't find it nearly as much as you would traveler. I once wrote colour on the board, and the students immediately stopped me in my tracks. The same goes for centre, practise and tyre. Having English teachers from six different English speaking countries doesn't change anything, even if most of them would write aluminium instead of aluminum.

Protons, neutrons, and electrons is a bad analogy. But you need not know more than the word pickup truck to know what to call such a vehicle, and the word lorry is just a synonym I'm nearly certain you won't find in a Korean middle school English textbook. However, you cannot understand the entirety of an atom without knowing what protons, neutrons and electrons all are, none of which are synonomous with one another. However, it would be perfectly reasonable to include car without automobile in the curriculum just as much as the inclusion of elevator instead of lift. On the other hand, you wouldn't want to include the words winter and summer, without mentioning fall or spring. Though I wouldn't do so, you can leave out autumn from that list, and the students will still have an English word for for 가을.

Please don't get me wrong, I like British English and saying words like jumper, trousers, or knickers. But I also like consistency for beginning English speakers. If anyone knows any good British English expressions, slang or whatever, please post it.