Vietnamese Class

Well I thought taking Vietnamese would be helpful in going to Vietnam. I have taken language classes before but Vietnamese is different. Well firstly, it is tonal so how you say things are different based on the tone. Ma and Má are two totally different words. The second thing is my classmates. Now they all seem to be nice people...well most of them. When you take a class like Spanish or French intro you expect everyone is trying to learn and everyone is in the same boat so to speak. In this class EVERYONE is connected to Vietnam. People are born there or grew up or in some cases speak Vietnamese fluently. Why you say would someone who speaks fluently go to an Intro class? They just can't write. Vietnamese is a language you have to listen to understand and differentiate the tones. So I am trying to learn why some People are having discussions about what certain words mean we have not learned yet while the teacher wonders how many times does she have to go over the vowels with me.