Some vocabulary researchers (e.g., Laufer & Sim, 1985) have stressed the importance
of high-frequency words for learners of English, because a relatively small
number of words constitute the bulk of words encountered in text. However,
the most effective methodology for teaching high-frequency words still needs to
be explored, given that such words are also the most likely to have multiple
meanings. Others have stressed the importance of focusing on words intermediate
in frequency—not so frequent that they are already known by almost
everyone, yet frequent enough to be worth teaching. Much remains to be
learned about identifying these words and about the effectiveness of instructional
approaches that focus on such words. Another dimension of choosing
words for instruction has to do with the relationships among instructed words.
Materials for learners of English as a second language often group words on the
basis of meaning. However, some evidence suggests that teaching words in
groups that are highly similar in meaning is a hindrance, rather than an aid, to
learning (Tinkham, 1993; Waring, 1997).