Two cases: we had friends who lived in Chile. The girls started school totally without Spanish; before the year was out, they spoke it fine. They didn't need teachers to speak English to them; they caught on.
I am tutoring a little Chinese boy; they speak Chinese at home. His dad told me, 'Last year he didn't speak any English; I think a teacher at his preschool spoke Chinese, and so he didn't need to. This year he is in Kdg; his English has improved dramatically.
What's wrong with immersion?? It is considered THE way to learn a language later on; all the missionaries use immersion. But it is not good enough for little kids, who pick up languages the easiest of all of us?
I think it is ok to have someone who speaks another language for the parents; the moms, esp., don't often speak English. But for the kids I think it is a waste of time and it works against what you want -- bringing them into OUR culture, teaching them English, helping them belong.
I prefer immersion as a teaching method. However, it isn't happening at DISD. Student population is now 63% hispanic...most of whom are illegals. Most of the teachers are the bottom of the barrel...if they could get a decent job, they'd move to one of the suburbs and teach. The horror stories that come from DISD are amazing. It is common, for example, for teachers to sit in class and read a book, and let the kids entertain themselves. Thank the unions for this...and the federal government for letting the illegals in and stay. Under these circumstances, I'd rather see bilingual teachers. They can teach by immersion method...but would be more prone to actually communicate with the kids rather than sit at a desk and do nothing.
The problem is where is no push by the parents to learn English. School is regarded as a baby-sitting service. I must admit that this is understandable when the driving force in a family is to get as much money as possible and local businessmen are trying to keep wages as low as possible.