I've known people who intentionally moved to a place where people only spoke the local language (and perhaps a few word of English) and they sent their children

I've known people who intentionally moved to a place where people only spoke the local language (and perhaps a few word of English) and they sent their children to a local school. It was incredible to see how effective immersion can be when there's no escape hatch. Of course usually it's difficult to pull off, considering how many locals speak English and how many non-locals tend to be around.