Thank you so much for your insights, Val! I also agree that immersion is the best method of learning a second/foreign language. We have an immersion school with a program in French in one of our public schools, and I went to one of the open houses recently. I am sad to say that I was very unimpressed:

* There were very few if any opportunities for cooperative and project-based learning; I did not observe any in the 5 classes I saw, but made a point to ask about it during the Q & A that followed. The principal hemmed and hawed, but admitted that the kids have time to do that "later, in the upper grades."
* There are no textbooks in the target language after kindergarten (although there are library books in the target language), so students were either reading in English or translating from English to French when called upon. How is biliteracy being promoted, especially when research indicates that once English language arts is introduced, kids typically shun pleasure reading in the target language?
* The facility is decrepit and looks as though it hasn't been updated since 1970. Not only is this an aesthetic issue, but also to me an indication of the district's support of the school. It was a red flag to me when I drove up.
* The school provides no opportunities for developing the kids' social language in the target language; the principal told me that they only have time to devote to "academic language."
* It is overcrowded.
* Some parents are very active in the school, but parental involvement overall is spotty at best.

I am very disappointed that this is not an option for us.

However, I've been to the dual-language school twice, and they are clearly using best practices. I like that the classrooms are a mix of 50% native Spanish speakers and 50% native English speakers, because this fosters the acquisition of social language, promotes cultural awareness and facilitates cooperative learning and project-based learning. At this point, it's our number one public school pick.

Thanks so much for the tips on what to ask at the 145+ school. The only thing that I can tell you is that the school does NOT have a problem with gaps. I asked about this at the open house and heard from both the director and a kindergarten teacher that this was normal and expected; also, my friend whose 2 kids attend the school told me the same thing, because her DS was a late reader, and her DD is still not reading fluently, but the school is very accommodating. That made me feel better. However, I'm interested in getting answers to the other questions you posed as well, and really appreciate your taking the time to give me this input--MANY THANKS AGAIN!