I read a LOT when I was younger (elementary and middle school).  My family didn’t have cable TV and internet wasn’t prevalent at that time, so I spent all my free time reading.  When I came across words I didn’t know, which was fairly often at that time since I was young, I just ignored them and read on.  I didn’t like to interrupt the flow and enjoyment of my reading to look up words all the time.  But I read so much that if it’s not a rare word, I was able to learn the meaning from context after encountering it a few times.  One word that I learned this way is “dilapidated;” I remember reading it twice in very short succession and I just knew from context what it meant.  After that, every time I read that word it reinforced my understanding of it a little bit more.

I can’t stress enough the importance of reading in improving a child’s language ability.  I went to the US when I was in the third grade of elementary school knowing zero English; English was not taught in elementary school in Taiwan at that time.  I remember going to ESL (English as second language) class (where all the other kids were Spanish because I was in Texas) everyday in third grade where they taught us English with Sesame Street puppets.  In the fourth grade, our class was divided into reading groups and I was already in the top reading group just because I read so much in my free time.    

I know adults don’t have the time to do this; I’m just sharing my experience.  Also, I think children’s brains are far more receptive to learning than adults, so I’m probably not able to learn in the same way today.  Now I don’t come across words I don’t know very often, but when I do, I will look them up.

Some new words I can remember easily but there are also others I can't remember correctly such as maintenance/ maintain. I see and use these words a lot but I always have to use dictionary to check dictation. Or misremember meaning between courage and encourage.

Lawrence, 

It is quite right, it depends on where you live in Viet nam. Foreigners just live in big cities or even in center area of big cities. I live and work in countryside  so I don't have many chances to practise speaking English . I use English at work but most in writing. We also use English to communicate but we are all non-native speaker and have own pronunciation problems. 

One more thing, it's also not easy to have a chance to practise speaking English even when you live in big cities. Because it's not easy to start a conversation with a stranger right ? You must prepare carefully how to have a talk with them in order to not not make misunderstanding or impolite in their culture...