The best practice that is proposed for the teaching of vocabulary is to teach it within context, and not in an isolated manner. The reason is very simple: Students need to make connections in order to learn. These connections are text to text, text to self, and text to world.
If you introduce a word and its meaning with no background support to create a schema or a knowledge concept of it you will only succeed at having the student store the word momentarily in his short term memory with no opportunity to use the word nor apply it the way that it is supposed to be applied in everyday language.
However, separating the word and RE-applying it within a context help create those connections that are essential for learning. The link included will take you to some of Enotes current documents on Text to Text connections.