[tetris11]

> many of my second-generation immigrant friends are now effectively monolingual because of that.

This is mostly to do "nervous spartan syndrome" from the parents, who are so anxious at losing their cultural heritage, that they overcompensate with their kids by correcting their pronunciation at every word, essentially punishing effort.

Families where I've seen this work well are the ones that take their kids yearly back to the old country to soak in the language with the locals. Of course, that implies money and time.