Agreed on what music is intended to do. But being expressive can mean understanding different scales, different rhythms, different harmonic progressions, the ca

Agreed on what music is intended to do. But being expressive can mean understanding different scales, different rhythms, different harmonic progressions, the capabilities of different instruments, etc. One thing I did not learn in my childhood music lessons is basic stuff like musical intervals, chord structure, circle of fifths. These are very practical math relationships ... essential to knowing about your options, for both expressive performance and for on-paper composition and arranging. In later years, I regretted that none of my teachers knew enough about them to help me understand them. They're an indispensable tool in the pro musician's arsenal.