I'm currently learning theory and need some help. I can't necessarily tell apart Major and Minor scales (from the key signature and the scales) nor can I tell the harmonic form. I remember my teacher telling me that the major scales have no accidentals, and the minors and harmonic do, but I do not know how to tell if a scale is minor in natural or harmonic form.
Firstly, from the key sig. Each and every major scale/key has a relative minor that uses the same notes, exactly. That's the natural minor. So, from the key sig. itself on the sheet, with 3#, it's either A major, or F# minor. Bb major or G minor has 2 bs. And so on.
From the sound of the scale, the third note is the defining one. It's either a major third or a minor third, slightly lower.
Let's now look at the melodic minor. Same first 5 notes as the harmonic and natural minor scales, but the notes 6 and 7 are the same as the parallel major. The parallel scales are those with the same letter names - C major/C minor; D major/ D minor, etc.
And now, the harmonic minor. That has the same notes as the natural with only the 7th note raised, to give a leading note just one semitone away from the root. That's done to sound more convincing than having a 7th scale degree like the one in the natural minor.
So, in summation - the natural minor has the same notes as the relative major. The harmonic minor has the same notes with just a sharpened 7th note - an accidental. The melodic minor has sharpened 6th and 7th notes, so two accidentals.
There are two melodic minors - jazzers use the same notes as the classical one (which I described) most of the time, whereas the classical melodic scale is as stated ascending, but it reverts to the natural minor notes descending. Confusing? I think so!