Study Jazz Blues Shells, an original twelve-bar jazz blues in F. Its left hand uses sparse two-note voicings, mostly root and seventh, with the third–seventh pair A–E flat in bar 4 and the diminished-seventh span E–D flat in bar 6. Keep those voicings light and even under the tune. At the keyboard: play shell and rootless ii–V–I voicings; those are separate models, not the accompaniment printed throughout this piece.