Learners should not be expressly taught that "A star shoots." is a grammatical, complete sentence.
Verbs like shoot, race, whiz, etc. (in the sense of move quickly) are rarely used without a complement, and a descriptive grammar must reflect this fact, as well as a good dictionary (see the usage note for each of the verbs in the Oxford Dictionary, the Longman Dictionary, etc.). For example:
Move or cause to move suddenly and rapidly in a particular direction:
[NO OBJECT, WITH ADVERBIAL OF DIRECTION]: 'the car shot forward'
[WITH OBJECT AND ADVERBIAL OF DIRECTION]: 'he would have fallen if Marc hadn’t shot out a hand to stop him'
One would think that if we choose a logical approach to grammar, we can draw parallels between the verb 'shoot' and some other verbs that don't require complements and have a similar meaning, and it will only seem sensible to rule that 'shoot' can also be used without a compliment. But language, as is actually used, does have countless illogical features and limitations. Many of these details have their own uses and benefits, and therefore should not be disregarded.
This problem is broader than it seems at first. Chances are you can find a bunch of verbs in your own language that you have to ask yourself: "Do they absolutely require a compliment? Can I use them without any?". Well, I had come across some in two other languages before, and now in English too. So, I'll try to answer with a broader view.
IMO, there are (at least) three different ways to perceive the rules of language, particularly grammar. We should separate these in our mind, especially when we want to teach a language to somebody. You may already know about the first two:
- the prescriptive approach
- the descriptive approach
- the logical approach
It's a made-up name :)
Prescriptive grammar is now considered obsolete and is frowned-upon by authorities. It tends to impose additional outdated and/or opinion-based restrictions and guidelines on language. It instructs you, for example, to avoid saying "I was shot.", "What are you talking about?", and many other decent sentences.
Descriptive grammar intends to reflect the way a language is actually used, by basing every rule on the way people actually speak, write, etc. You go as far as the usage goes; beyond that, no. You have to respect the detailed conventions of usage.
For example, if you hardly ever hear someone use the verb shoot (in the sense of move quickly) without a compliment, you deduce: Shoot must not be used without a complement.
The Logical approach is a name I made up to describe the way I see liberal-minded people (including myself) sometimes tend to use the language: to relax unreasonable conditions and limitations, and make language rules more symmetrical and simple. Here you extract some basic rules from the common usage (as raw material), and, taking a step forward, analyze those rules and see if there are any ways to expand them consistently, or relax some limitations.
As an example, take the verb shoot, which is not normally used without a complement. But we can draw similarities between shoot and some other verbs or verb phrases (e.g.: accelerate, move quickly, etc.), and judge that it's passable to say "A star shoots." without a Locative Compliment.
Mind, I'm not saying that anything is permitted in logical grammar. For example, "A shoots star" is impossible because there are no similar constructions: it's an inconsistent stretch.
One important difference between the descriptive and logical approaches is how they handle absence of evidence. In the former, you look for a construction in a large corpus to judge its validity, and if you don't find evidence, you avoid it. But in the latter, absence of evidence is not necessarily reason enough. There are other consistency considerations, e.g.: simplicity and symmetry of the rules, similarities, etc. (One might also add other factors like comicality, wittiness, etc., but then one should look for a title more apt than logical approach; something like innovative approach would be nice then.)
Now, when we want to teach someone a language, what approach should we choose? The descriptive one of course, because that's the one that describes the language as it is.
Is the logical approach of any use then? It is indeed.
For instance, many times people reform the structure of a sentence to give an ironic ring to it. You may want to alter the usual order of some adjectives or use shoot without a complement or even create a new word for humorous or emphatic effect. Note that this kind of effect would be less possible if it weren't for the asymmetries of the language (e.g.: if there were no adjective order, changing the order would be of no effect).
Furthermore, if people were to always follow the same words and constructions, languages would never have changed, and the same things would have been repeated forever. But we all know that's not true. Languages do change for many reasons, one of them being the fact that people just love to be creative, to bend and break the rules and realize new possibilities. Shakespeare himself is believed to have invented hundreds of unprecedented words and expressions.
But that is not to say that learners should be introduced to conventional rules and innovative/logical ideas at the same time. You have to master the standard language first. If you jumble up half a dozen "logical" abnormalities in one sentence, you'll only get yourself laughed at, and get bad grades in your exams.
I would ramble on about the relation between conventional and innovative approaches, but I'm not an expert, and also my English is not yet good enough to give proper explanation with illustrative examples by well known authors or by myself. As a learner, I'd rather stick to the descriptive approach for now.
I've talked too much already anyway. But with the dispute in the previous postings, I hoped a longer answer would be fitting.