There is also the issue of approach: learning the grammar of a foreign tongue before the rest is tedious and will bring kids very little. If, however, you learn my immersion and naturally, then you are sure to be hooked. That's how I learned English anyway, on my own.

I ended up learning Japanese later in life through tons of immersion and living in the country, and knowing what I know now I wish I could have explained how important bilingualism is to 15 year old me...or even my dad. It is the single most eye-opening thing I've ever done. Something about it just makes you so much more cognoscente about everything you say and do even in your native language. It's like I "came online" or something.

When I was born, my mother specifically requested that she teach me to speak Spanish. She refused to do so; when her own children were born, she had been forbidden from teaching them Spanish.

It goes something like “I need to learn X; let me take a course on that, surely this will do it.” But then two things happen: the feeling that, by taking the course, you are doing what needs to be done in order to learn, you get lazy and sit back and expect it to happen passively. It won’t. Second, your teacher might not actually be very good, which is fine (most of us have no idea what constitutes “good teaching” in any repeatable way) and might give you lessons and assignments that may be more of a waste of time than anything else.

My point is: if you want to learn something, just go and do it. Odds are you are probably doing better than if you were in a course. If you are doing a course, then consider it as “time slot allocated to X” and try to be as independent and proactive as you can; it is much better than relying on a teacher.