I created this visual to help students see and hear the distinctions between the three types of minor scales.
I always think of a natural minor scale as a bit sad or melancholy.
The #'d 7th tone of the harmonic scale adds a creepy sounding appeal and of course makes the V7-i progressions sound so much more resolved, which is probably why the majority of minor pieces use the harmonic scale form.
Mixed Up Melodic
I think of the melodic minor as kind of a "wanna be" major. As the scale ascends, it starts with that distinctive minor flatted 3rd, but then the #6th and #7th tones almost trick you into thinking its a major scale until it returns to the natural minor form as it descends.
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On my previous post "Teaching Scales with a Story" learn how to introduce these concepts to students in a memorable fun way.