Problem of teaching someone to say something

[Niko]

Consider the problem of teaching someone to say something. What is it we are most concerned that they learn? Certainly not the mere mouthing of the utterance, the mere ability to pronounce the words. Certainly not the mere demonstration of ability to understand the utterance by, say, translation into the learner's own language. Even the combination of the two goals is not what we are after: it is not saying and understanding that we want but saying with understanding. That is, we want the learner to be able to use the language we teach, and we want the learner to be able to extend their ability to new cases, to create new utterances that are appropriate to their needs as a language user.

Learning a finite set of rules and a finite lexicon enables the learner to produce and interpret an infinite number of new well-formed sentences.

Understanding the rules and applying them is so much more powerful then simple memorisation of sentences.