A short chord progression plays, with a marker hovering over each chord. The last card stays blank — listen to the chord that plays there and pick it from the key's chords, laid out in order (C Dm Em F G Am B°). You start with I, IV and V; each level unlocks one more chord until the whole key is in play, and progressions grow longer. Later on the target chord comes voiced in inversions — you'll name the chord, then say whether it's root position, 1st, or 2nd inversion.