I think all of you here are learning, or has learned a foreign language. What I want to say here is how I learn, and after that, how I speak that language.
When I learned English, my teachers gave me a bunch of structure formula, how a sentence is made up, when to use singular or plural, etc, stuff like that, you know. When I took the exams I did remember SOME of it. But when I speak English (like to an American), these formulas and stuff are out of my head. I don't even remember any of them now. But I still speak English fluently (although I do make mistakes)
But the same cannot be said about my first language. I forgot the formulas the moment I learned them, and I still speak it fluently, make sentences and phrases that can NOT be understood (maybe) by a foreigner who knows how to speak Vietnamese. Of course the same applies when an American said something and I don't get it.
What makes that difference ? Should we reconsider how to teach a foreign language ? Should children be taught multiple languages when they're still very young, or just their mother tongue ? How can we learn to speak a foreign language as fluently as our mother tongue?