One of the most challenging questions I ever got in a class wasn’t an advanced question, but rather a very elementary one on sentence structure. Almost all linguists assume that in a sentence The queen saw the corgi that you separate the subject from the rest of the sentence (the predicate) instead of grouping the subject and the verb together (see below).
Right: [S [NP The Queen] || [VP fed [NP the corgi]].
Wrong: [S [VP[NP The Queen] fed] || [NP the corgi].
Why is this? On the surface, it appears to be an arbitrary division, but there is a reason behind this. After a good 30 second pause, I remembered what it was which is that linguists assume that sentences constituents are meaningful units by themselves (yes we do work with fragments). Thus you can have a exchange like “What did the Queen do?” “Feed the corgi”, but an answer “The queen fed” is not as natural. Hence the assumption that verbs and direct objects form a unit apart from the sentence.
The above is interesting, but the point isn’t really about linguistics but whether an instructor can remember why their discipline makes the assumptions that it does. To me it makes the difference between teaching your course as a coherent set of related concepts versus a random list of rules and facts. I was both relieved and thrilled that I could answer her question – another student convinced that we knew what we were talking about.
Every now and again a student asks why I torture them with analyzing a set of random words with ridiculous sounds from languages they’ve never heard of. When I remind them that sometimes this is all data on a language that an archaeologist or anthropologist may ever get, they realize that the homework isn’t just a torture device but a way to join a community of active researchers.