A question for the music educators out there. What are we doing wrong that is causing so many young musicians to ask so many questions based on the misapprehension that only certain notes and certain chords are "permitted" in a certain key?
From a classical training on piano, where no teacher actually explained that the scales I had to learn would be useful - they were merely something I would have to play in the exam, to realising, 30 years later, that they were in fact the basic formula from which a tune in a particular key could be made. It was long, hard journey, but for many years now, I taught that the scale notes , when kept to, would sound better than most other notes for a certain key. When pupils get to around grade IV level, I feel it's worth throwing out that 'rule' and I say - to guitar students - "Any note, any fret, any string, anywhere in any bar CAN (not will!) fit. Then the fun starts. Fit a couple of Bb notes into a tune in A major, etc.
BUT - initially, the 'rule' does work, it's safe, it makes sense, so I feel it can be taught. Remember when you were about 4 or 5 and you were told you couldn't take 6 away from 5? At that stage, on a need to know basis, that's all you needed to know!
Maybe those questioners have only reached the nursery slopes, maybe their teachers aren't as thorough as we'd like, maybe they want to stay 'safe', maybe they feel the student isn't ready, I don't know.
What are we doing wrong? Sounds like teaching theory more than actual pieces. If we never taught theory there would be no concept of key, scale, or chord in a limiting or structural sense. If we taught mostly pieces that challenge (or flat-out reject) typical western music theory and structure, then there would be less of a perception of the theory as being a set of rules to be followed.
It was only after a year and a half of college music theory that I realized theory is really more an attempt to explain why creative people came up with what they did. I stopped believing that great composers were actually thinking "ok I need a secondary dominant here so let me run down my list of chords that can fit that role". I don't think we really discuss that very much in teaching but maybe we should.
Edit: Answering as a student rather than an educator.
The biggest factor for me was starting with and focusing on only classical music for years. This "play what's on the page, as perfectly as possible" and a focus on the key signature instructing what "valid" notes are led to my personal conclusion that you must perform in key and block out notes that aren't. Even the term "accidental" seems to imply that an off-key note doesn't really "fit" with the piece.
Second, scales are hammered in so heavily whenever you're learning a new key or style along with the wrong messaging. Here's what I took away from my learning - Classical - play your scales with the perfect fingerings, and stick to the notes in the scales. Blues - here are the notes in the blues scale, start improvising using one note, then move to two, then three and on up until you can improvise across the whole scale, but stay within the scale. Jazz - figure out what scale or mode fits best with this harmony and stick with that.
I think the correction to this is teaching students how and when to use notes that are off the scale. For example, starting with crush/grace notes running from minor 3rd->major 3rd, or songs like "Gimme Shelter" which sound great but it's pretty hard to define what key the song is in since the verses are in C#, and the chorus follow a C# B A progression. Hearing is believing in this case, and so, I always wish I had a teacher who showed me some of the riffs that would sound great but play outside the notes that are considered "in key". Instructing in improvisation or writing melodies and solos may help here too, or perhaps even exercises that require the use of notes outside the "defined" key.
I had always thought exactly what you said - that I must remain in key, and only after reading a lot of the posts here and asking questions about "what key is this progression in?" have I realized that the key of a song can be subjective, and that it's a guideline more than a rule. And since I've realized that, my improvisation skills have opened up considerably.
I find it a bit depressing to see a lot of questions refer to a musical situation as "acceptable" or even "Correct".
I think there are three ways of going about making music:
1) Classical/formal training: Learn to play (often amazing) pieces of music written on a page. I've never done this so I'm not going to say too much about it, but having played with a few people trained in this way, their paradigm does seem to be that there is right and wrong in music and the percieved rules of music theory is king. I don't mean that everyone who is formally trained thinks that way of course, just that of the people I've met, they've had a more regimented approach to music.
2) Find your own way: Pick up an instrument and learn by trial and error how to make it sound like those who inspired you. You'll devise your own music theory, albeit only as far as you need to in order to achieve the style you're after.
3) Forget the dogma and just make some sounds. Use a guitar or a coconut if you like. Music is sound so make sound.
I personally used methods 2) and 3). I've recently learnt a LOT through StackExchange (thank you!) about music theory and realised that to my amazement, there are names for things I've discovered myself over the years. I've found these things (eg the various musical modes) by noticing that they exist then discovering the name. I can see that if it were the other way around, and I was shown them then I might percieve them as a 'rule'.
From what I've seen on the internet and talking to colleagues, I think method 3) is missing in a lot of musical teaching- or a reminder of it at least.
The answer to the question "How do I play guitar?" (which I'm asked now and then) is "Make a sound with it. It has strings so you can make different notes as well."
Trouble is when I've explained that to students, they look at me in bewilderment lol
I would like to answer this as a music student who has studied harmony, modern harmony and counterpoint for the last years and I find myself asking the same question as well as others in the same context. I have yet to see a theory method that focuses on the creation of the melody, rather than its harmonization. Also, minimum and untimely attention is given to chromaticism and ornamentation. Using scales is just a failsafe method to compose and it sometimes seems like the only logical (or right) thing to do.
There is nothing wrong; it is the order of things. Teenagers find out that driving (and love) is not what they learned in school. College kids find out that their degrees do (and don't) prepare them for their careers. Parents find out that despite all the books, they just sort of make it up as they go along and hope for the best.
Music students find out that the vacuum of captive theory can only be used in conjunction with other tools to describe the music of untamed wild.
They are asking the write questions; you cannot shatter a foundation you have not yet laid.