How exactly does this apply to, say, the African American segment of the population, many of whom have been in the US for hundreds of years and most of whom know no other language than English?
"English" (at least as practiced in the USA) is not a singular thing. Go have a conversation with a "native" English speaker in inner city Baltimore or the backwoods of Georgia and I suspect that you'll spend a lot of time asking people to repeat themselves.
edit: well someone apparently thinks this comment doesn't add to the discussion, so let me try to clarify: most everyone speaks "English" in the USA, but not the same "English". There are accents of course, but there are also different terms to reference the same thing ("pop" vs "soda" vs "coke", "grinder" vs "sub" vs "hoagie"), different pronunciations ("ask" vs "aks", "nuclear" vs "nukuler") and then you have regions like New Orleans where foreign words are regularly mixed in with English.
For those that have the time, I recommend slogging your way through this ArsTechnica thread for a more in depth explanation of what I'm trying to say: http://arstechnica.com/civis/viewtopic.php?f=23&t=112892... (if you don't have a lot of time, start on Page 3)
I see what you're getting at but the examples you give- everyone knows what all of those words mean. Someone may say "pop" but they still know what soda is. People who say "aks" are not confused by the word ask.
Well those weren't exhaustive examples, but I'd still disagree - for the longest time, I though "hoagie" was a polish food (I grew up in "grinder" territory) and I was mystified the first time someone asked me to pick up an "orange coke" at the drug store.
Another example: http://www.youtube.com/watch?v=03iwAY4KlIU it's all English, and you can often get a general meaning from context, but the vid gives examples of words I've never heard, or more familiar English words used in combinations that obscure the meaning. So of course you can take someone from the video and drop them in NYC and they'll be able to function, but there will likely be things they miss and things NYCers will miss talking to them. Now in a school environment, that can make a huge distance.
Further illustration: In my area, I hear both "sub" and "hoagie" used to refer to different varieties of the sandwich. I'm not positive what the dividing line is, but it seems like hoagies are generally less healthful than subs.
"English" (at least as practiced in the USA) is not a singular thing. Go have a conversation with a "native" English speaker in inner city Baltimore or the backwoods of Georgia and I suspect that you'll spend a lot of time asking people to repeat themselves.
edit: well someone apparently thinks this comment doesn't add to the discussion, so let me try to clarify: most everyone speaks "English" in the USA, but not the same "English". There are accents of course, but there are also different terms to reference the same thing ("pop" vs "soda" vs "coke", "grinder" vs "sub" vs "hoagie"), different pronunciations ("ask" vs "aks", "nuclear" vs "nukuler") and then you have regions like New Orleans where foreign words are regularly mixed in with English.
For those that have the time, I recommend slogging your way through this ArsTechnica thread for a more in depth explanation of what I'm trying to say: http://arstechnica.com/civis/viewtopic.php?f=23&t=112892... (if you don't have a lot of time, start on Page 3)