Let's call them the study and the laundry. One more, the Seven chord, that half-diminished, we'll call the bathroom. Don't let it scare you. It never realy comes up. So there it is.
All rooms connect and are laid out in a fixed way.
That's one key. All music is a twelve storey apartment block, twelve floors of identical layout. The Music Building. So, each key consists of seven chords, laid out identically. If you know one, you know 'em all.