I am sure all teachers behave in a professional manner, regardless of their nationality. The differences between British English and American English are not so much to do with grammar, but rather with accent, word usage and meaning and colloquialisms. Basic English grammar doesn't vary that much - although my American cousins do have a annoying habit of turning nouns into verbs - I do hate when the Olympics roll round - every time I hear someone is going to 'medal' I feel like throwing something!