Why do we need words?
Words are powerful carrier of meaning. A student who says 'Tomorrow. Go library. And classmates. Borrow books' will certainly get much of his message conveyed despite the lack of accuracy in grammar. Yet, a person who has solid knowledge related to grammar but limited vocabulary may not be able to communicate well with others. 'I was wondering if I could use your ...' means little without a word to fill the gap, whereas the missing word -bathroom- on its own could possibly convey the desired message: 'Bathroom?' It is therefore important for learners to understand the notion of a word and how different words can be learnt.