Best Practice 23: About Dictionaries
Students should always try to guess the meaning of new words from the context (see BP21 for further explanation). If all else fails, however, ask them to use a monolingual English-English or Visual dictionary. Not only is such a dictionary an important source of supplementary knowledge for a student, but it also makes the student more self-assured and better equipped to engage in independent study
outside the class.
Dictionary selection is a complicated thing, however; not all are created equal. Some are simply out of date – one that is more than five years old, for example, will almost certainly ignore the recently added connotations of the word “mouse” - while others do not include phrasal verbs like “look out for”.