One grammar activity required students to place the given jumbled words into the correct order. One of them involved an indirect question, approximately “Could you tell me where the station is?”. All the students wrote “Could you tell me where is the station?”. This fits the pattern for a direct question (“Where is the station?”) and is perfectly understandable, but no native speaker over the age of three ever uses that structure, or is ever explicitly taught the rule.
It sounds a bit wishy-washy to say “In this kind of sentence we use this order and not that order” without giving some sort of reason, especially when there’s such a strong pull towards that order (viz, the subject-auxiliary inversion of a direct question).
But grammar books and websites don’t give a reason. Even the monumental Cambridge Grammar of the English Language (which I have just bought, so I’m likely to quote more, in order to get my considerable amount of money’s worth, says only:
The main structural difference between subordinate and main clause interrogatives is that subject-auxiliary inversion does not generally apply in the subordinate construction.
But why not? If absolutely every native speaker doesn’t do it, there must be a reason.
As far as I can figure, our unconscious reasoning is this: we know “The station is somewhere”. We want to know “where”? We could ask “The station is where?” (and we sometimes do, but only after someone else has just said “The station is mumble” or “The station is [some surprising place]”. But most of the time we bring the question word to the front and invert the subject and auxiliary: “*Where the station is? > Where is the station?”. So the first question is actually “Why do we invert the subject and auxiliary in direct questions?”. Some/?many languages don’t (Korean that I know of; it doesn’t have a separate word corresponding to it), but English does. I don’t know why, and can’t hazard a guess.
The indirect question is essentially “Could you tell me something?”, and that something is “where the station is”, so the whole question is “Could you tell me / where the station is?”. It’s clear to me, but it’s unclear to every student I’ve ever taught it to. Maybe “Could you tell me where is the station?” will become standard English as a second language, with “Could you tell me where the station is?” remaining standard English as a first language.
Another grammar pattern which raises the question of why? is the order of adjectives. Another sentence in the same activity involved “*a new nice spotted dress > a nice new spotted dress”. Opinions come before age come before size/design, but why?
These kinds of grammar activities are interesting, because most students come very close, but there’s one issue arising. Some, though, just produce word salad, and I really can’t tell what they are trying to say or how they are processing English.