Harmonizing a major scale with three note chords or triads creates a wonderful sequence of chords that can be used to play a wide range of music.  There is a basic formula for this sequence, which is often described using Roman numerals with an upper case numeral being a major chord and a lower case numeral being a minor chord.  Here is the sequence for a harmonized major scale:

  • I ii iii IV V vi vi(diminished)

Notice how the 7th chord in the sequence is diminished.  All the others are either major or minor.  The I, IV and V chords are major.  The ii, iii, and vi chords are minor.

In the key of C this would translate to:

  • C Dm Em F G Am Bdim

It is common to substitute a V7 chord or G7 for the B diminished chord.  In the video lesson here we will explore these chords in 1st position.  Once you are comfortable with them and have the progression memorized you will begin to see how chord progressions work.  A common chord progression is I vii IV V for example.  In the key of C this would be C Am F G.  If you already know some chord progressions in the key of C, try to analyze them to understand how this system works.  If you find a chord in a song that is not part of this harmonized scale it is likely because accidentals or notes outside of the key of C were used for a moment.  This can create variations on the sequence.  A few common alterations of chords are minor IV chords (Fm in the key of C) or VI7 II7 V7 I patterns (A7, D7, G7, C) which is common in both Swing and Hawaiian music.