I found this article to be pretty interesting. (If you don’t read French, Google translate does a decent job here.) It’s about something that is a rarity both in the US and in Québec: a single elementary classroom with double the standard number of students and two co-equal teachers. The article profiles the class with photos and background.
The main advantage, according to the article, is that the students can take advantage of differences in how the two teachers approach explanations, doubling their chances of understanding. It follows from this that math is where the greatest advantage is seen (because understanding a lot more explanations is required). There are other advantages, for example one of the teachers can go one-on-one with a student having trouble without abandoning the rest of the class.
The class is structured so that students spend a considerable amount of time in independent activities; perhaps this is also a side-effect of the co-teaching method, since both teachers circulate among groups and individuals, thereby doubling the available interaction with students.
I was wondering whether any of the teachers here have tried or know of this kind of approach in the US. The article is very positive and suggests that the number of classrooms using this method is increasing in Québec, but perhaps there are difficulties that also arise?