Not a vocabulary you memorize. Tap the circle — every dot is a note, and the outline is a scale.
That outline never changes shape. Move it to another note and you have another key — same geometry, new position. Twelve keys is one thing learned once, not twelve things memorized.
A root note hums and never stops. Some notes blend with it, some fight it. Nobody tells you which — your ear already knows.
The band calls a key and the clock starts. Four scenarios that go wrong the way real gigs go wrong.
Generate a practice lead sheet for any tune — chord symbols, the right register, and a B♭ transposition toggle. Print it and take it to the stand.