'Trousers' or 'pants'? 'Lift' or 'elevator'? 'Colour' or 'color'? 'Theatre' or 'theater'? Which lexical item do you use? Which form of spelling do you opt for? Do you teach 'American' or 'British' English? Or both? How do you decide what to teach? Does it matter? Well, according to some recent research, it does matter, and if current trends continue, it might matter even more in the future. The study, called The Fall of the Empire: The Americanization of English, analyzed over 15 million digitized books published between 1800 and 2010,...