This is a really thoughtful educational approach. Let me think through this with you.

In Sanderson's style, he often takes one fundamental magic principle and explores how it interacts with his world's physics, culture, and plot in increasingly complex ways. Think of how Allomancy in Mistborn starts with simple metal-burning concepts that children can grasp, but develops into intricate combinations and theories that reward deeper understanding.

However, music theory is inherently interconnected - the relationship between tonic and dominant (V-I) can't really exist without understanding chord function, which relies on understanding major/minor tonality. It's more like a language where grammar, vocabulary, and pronunciation all work together to create meaning.

Given your educational goals, what if we structured it like this:

The fundamental "magic" could be the concept of musical tension and resolution itself - the natural force that makes certain combinations of notes want to move in certain ways. This is something even young piano students can feel intuitively when they play - some combinations feel "finished" while others feel like they need to go somewhere.

Then we could layer in the other musical concepts as different manifestations of this fundamental force: - The tonic-dominant relationship becomes the strongest expression of this force - Major/minor tonalities affect how this force manifates in different regions - Voice leading becomes the specific "rules" or "paths" this force creates

This way, beginners could grasp the basic concept of musical tension (like how superheroes have a basic power), while more advanced students would recognize how this maps to specific music theory concepts they're learning (like how superhero fans pick up on deeper comic book references).