You are talking about success in other subjects, such as math. What happens if someone whose mother tongue is English has to take some subjects in French and some in English? Does that provide additional challenges? You are saying that studies show that that is not the case, but does that depend on how old students are when they start? Do students have to start at a younger age for the program to work and for them to do well in school in a situation like that?
On June 11th, 2013. See this statement in context.