Listen up y'all
This post by Ben Trawick-Smith on Dialect Blog is a really concise and fascinating insight into the migration of a phrase from Scotland to Ireland and then to the south of the USA and up to the northern states, spreading out from its original usage base of poor white farmers to African American slaves and then into wider multiethnic usage.The expression is y'all and it's a second person plural pronoun (as distinguished from you which acts as both 2nd person singular and plural in Standard British English). For a neat little case study into how language spreads, which could be perfect for A level, go no further.
