·         Sevenths and related chords account for much of jazz harmony.

·         There are three main types of seventh:

          Major seventh (maj7, M7 or Δ7)

          Dominant seventh (7)

          Minor seventh (mi7,-7)

·         A general rule in playing chords on keyboards is to spread the notes out leaving lots of space at the bottom.

·         For example, you could play CΔ7 as in Example [2.1], but the texture is too heavy.  So let some air in by moving the middle two notes (E and G) up an octave (Example [2.2]).  Doesn't that sound better?

·         You can do the same thing for C-7 (Example [2.3]) and C7 (Example [2.4]).

·         The I VII combination played in the left hand in Examples [2.2], [2.3] and [2.4] is called the shell.

·         The combination of left-hand shell and the rest of the chord in the right hand is a simple but effective way to voice a chord progression and turn it into an accompaniment.

·         The shell is also a good left-hand basis for improvisation.  As the right hand plays out a melodic line, notes in the line will fill out the chord as they pass.

·         Practice all the major and minor seventh shells.  Experiment with different right-hand notes and listen to the effect.  Examples [2.5], [2.6] and [2.7] are complex forms of C7.  [2.8] and [2.9] are C- variants.  [2.10] is an extended form of CΔ7.  What do you think their chord symbols should be?