Now, please do not take this post as an insult to people who are immigrants, as my family immigrated to America. But, you bet your bottom dollar that they taught themselves the language and knew it well. Bottom line - We need to stop band-aiding the problems in this country and get to the root before it's too late.
My great grandmother never spoke a word of English in her life. She couldn't teach her kids English. They learned it at school. This problem isn't new - - my grandfather went to a poor inner city school where if you flunked out, you flunked out and no one cared. Getting an eight grade education was enough - his high school education was more than adequate for a good union job at the factory post WWII. That's a little different than the "no child left behind" mentality, mandated testing and very few decent paying jobs available for someone who only finished high school.
(My other grandfather grew up near New Ulm Minnesota - when he went to school it was still taught in German as well as English - lots of families didn't speak English at all - and my grandfather and lots of his German speaking neighbors were a third or forth generation Americans - he was born in the 1910s and his family had emmigrated to the U.S. in the 1820s - he didn't finish eight grade, and raised a family as a machinist. )
Things are very different now, but they are also very much the same.