Ed Sheeran’s “Perfect” from ChordTime Piano Hits may be the favourite wedding song of our generation. It also happens to be the perfect song to learn four chords that define western popular music: I, vi, IV, and V. These chords surely sound familiar by now—they’re the same four chords we looked at last week. If you’ve thought about teaching your students to write pop songs, this one is a beautiful model. It employs a waltz-like compound meter (the beat divides into three, rather than two). Sheeran also breaks up the chord progression for the bridge, simply altering the order of the four favourite chords to: vi, IV, I, V.