By Karen Stanley - Central Piedmont Community College, North Carolina, USA
Guessing meaning from context is a valuable skill to develop, but so is how to use dictionaries properly. I feel there is a place for bilingual dictionaries, learners' monolingual dictionaries, and native speaker monolingual dictionaries. Of course, just as you may need to teach the skills for guessing from context to some learners, you may need to teach them how to use dictionaries in an appropriate way.
Just the other day, in a key sentence in an advanced reading assignment, I asked students what word X meant. They provided me with four or five different possibilities, ALL of which made sense in the context, but NONE of which conveyed the meaning that was key to understanding the author's perspective.
I will never forget the time, now many years (20, maybe?) ago, when a key word in a paragraph was AFLOAT. One good guesser-from-context with a knowledge of prefixes (taught in class) assumed that the A- represented "without, not" rather than "in a specified state or condition." Nothing in the context (a real article from a magazine) indicated which meaning the prefix had, yet misunderstanding the meaning changed the answers to several questions on the test. That was the moment when I stopped forbidding dictionary use on tests (or in any type of reading assignment).
As a side note, I do encourage students to underline unknown words as they read rather than looking them up. I tell them to finish reading the whole item first, and then go back afterward to see which ones they feel they still need or want to look up.
When I am writing something, and I need a word that I can't remember or never knew, a bilingual dictionary is invaluable. If it's just that the word is on the tip of my tongue, a quick glance in my bilingual dictionary is often rewarded by - oh, that's it! If I don't see a word I know, I will sometimes use a corpus to pull examples of the word to see how people are using it in a sentence/paragraph.
Of course, you have to be careful, and I often double check a word by looking it up in the opposite direction. Also, obviously, some of this is only when I have enough time, but it can be valuable in building my vocabulary skills - especially when there are no native speakers around to help.
In reading situations, a bilingual dictionary can be helpful when I want to ensure that I have understood something correctly - bilingual dictionaries are much quicker than then having to decode the meaning in the same language as the original text.
Learner dictionaries I find especially useful when I want examples of how to use a word and don't have time to search (or perhaps access at that moment) corpora for examples that fit the way I am considering using the word.
Monolingual native speaker dictionaries are most helpful (for me) when the word is at a level of knowledge such that it does not appear even in more extensive learner dictionaries.
Of course, there will always be vocabulary that can't be guessed from context OR found in a dictionary!