Hear a chord, name its quality
One chord plays; you say what kind it is. Major and minor first, diminished and dominant 7 as you level up. Ten questions a round, answers revealed immediately, and the chords are voiced the way you'll meet them in songs — not always as tidy stacked triads.
The color, not the spelling
Chord quality is the emotional color of harmony: the difference between a bright chorus and a dark turn is usually one quality change. Recognizing it by ear is what lets you follow a progression in real time — hearing a song's shape before you ever look for a chord chart. Spelling chords on paper is theory; this drill trains the sound.
Build the full harmonic ear
Qualities are step one. Next comes hearing how chords pull toward each other — try After the Cadence and Find the Way Home for that pull, or step back to the scale degree trainer to anchor single notes first. The chords lesson has the five-minute theory version.