Though dictionary work is certainly useful it is time consuming and there is often more than one meaning. This may confuse sts. Also, it’s not the most memorable and fun way to learn new words.

Then we have bilingual dictionaries, which are not much use if you have sts from several countries. Many words don’t translate well and you will not be able to make sure they are all correct, as you don’t speak all the languages.

Additionally, when sts look up a dictionary the pacing becomes heavy and less dynamic.

So though I do think dictionaries are important, bear the above in mind and maybe not rely too much on them.