You know, I thought that "Thanh" looked Vietnamese.
I can't learn any language, classroom or otherwise. My ears don't catch sounds very well and my mind doesn't process aural information that quickly. Add to that the fact that spoken languages are taught inductively and there you go.
The one and only language I have ever learned is Biblical Hebrew, which is a textual language taught deductively and learned visually (letters on a page). Plus I had almost supernatural motivation to learn that one. It remains to this day my one and only language success; I haven't even been able to learn Israeli Hebrew.
There is something mysterious and incantational about liturgical languages that makes them more appealing than mere everyday conversation in another language.
I am keeping up with written Vietnamese pretty well because I write back and forth to a couple of nuns in Cam Duc. I also trade email with several other folks almost daily. That started out as quite a challenge because over there they only have INET access at INET cafes where none of the machines have Vietnamese fonts. So they write to me in Vietnamese with no marks. Each word can have a couple dozen different translations. I am getting the hang of it now and don't have to use my dictionaries so much. I write back in a proper font. One 15 y.o. girl that I email with is a fanatic about learning English so she can get rich when the VC lid shatters in a couple of years. She writes to me in English and I write back in Vietnamese.