The common way of introducing new vocabulary is giving a list of words with translation. This kind of exercise does not require a lot of mental effort, that is why retention is not too long. There are other ways of presenting vocabulary to students, one of which is making them deduce the meaning of words from context.

The essence of this approach is that students study a text with the target vocabulary highlighted, and infer the meaning of words from context. However, students have to be taught what contextual clues can help understand the meaning of a word. Let us consider some of them.

1)                           Synonyms, that can be introduced with the phrases in other words, also known as, sometimes called, or;

2)                           Antonyms, which can be preceded by the phrases but, in contrast, however, instead of, unlike, yet;

3)                           Definition or rewarding – is defined as, meaning, the term for, that is;

4)                           Morphology: prefixes, roots and suffixes;

5)                           Parts of speech – which part of speech it is and surround it;

6)                           Proper names – help to use the students’ prior knowledge to understand context;

7)                           and Punctuation – synonyms, antonyms and definitions are often separated by a comma or a column.

Other techniques of vocabulary inference:

Substitution – think of a familiar word that can fit well within the context.

Use of general knowledge of the world and logic.

Though some researches state that it is not proper to guess vocabulary from context, as guesses are not always right, I think, vocabulary inference techniques should be taught. They are especially useful for those students who are going to take exams in the nearest future.

References:

http://www2.aasa.ac.jp/~dcdycus/LAC97/guessing.htm

http://www.mc.cc.md.us/faculty/~steuben/public_html/vocabularycontext.htm