A hierarchy of notes

Many guitarists learn and memorize diatonic scales, pentatonic scales, and triad arpeggios as three separate concepts, but they are intimately related, and it’s beneficial to learn each as an overlay on the next.

Let’s say that we’re playing over an A minor chord in fifth position. The most fundamental notes are the A notes — our tonal center. We’ll mark these in red:

The A minor triad adds two more notes relative to the A root, a minor 3rd (C) and a perfect 5th (E), which we will mark blue. These form the fifth-position A minor triad arpeggio:

The A minor pentatonic scale adds a perfect fourth (D) and a minor 7th (G), which we’ll mark in cyan:

As I explained in Hiding in Plain Sight, every pentatonic scale form contains “the rectangle”, in which we can overlay the missing notes to make three diatonic modes. In the case of the minor pentatonic scale, we add the 2nd and 6th scale degrees, marked in black:

The coloring gives us four classes of notes inside each diatonic mode:

1. The red notes, the tonal center of the scale, are the most consonant notes you can play over an A minor chord.
2. The blue notes, the other parts of the A minor triad, are also very consonant. They’re great notes to emphasize when the chord changes to A minor.
3. The cyan notes, the 4 and the b7, round out the pentatonic scale. They’re slightly less consonant, but are great for bending up and resolving to the 5 and 1 respectively.
4. The black notes, the 2nd and 6th scale degrees, are the characteristic notes that define the sounds of the minor modes. The natural 6th shouts Dorian, and the minor 2nd screams Phrygian. The 2nd and 6th are both great passing tones, and the major 2nd can also be an excellent note to highlight in a Dorian or Aeolian context…it has just enough dissonance to create interest without ever sounding bad.
   

The major modes

We can take the exact same approach with the major modes.

Let’s say that we’re playing over an C major chord in fifth position. The most fundamental notes are the C notes — our tonal center. We’ll mark these in red:

The C major triad adds two more notes relative to the C root, a major 3rd (E) and a perfect 5th (G), which we will mark blue. These form the fifth-position C major triad arpeggio.

The C major pentatonic scale adds a major second (D) and a major 6th (A), which we’ll mark in cyan:

And again, we can fill in “the rectangle” with the two missing notes to make three diatonic modes. In the case of the major pentatonic scale, we add the 4th and 7th scale degrees, marked in black:

The four colored classes of notes behave very similarly to the classes described for the minor modes.

And that’s not all

You may have noticed that the shapes in figures 3-6 are exactly the same as the shapes in figure 9-12. That’s no coincidence. The A minor pentatonic scale has exactly the same notes as the C major pentatonic scale. Furthermore, A Dorian has the same notes as C Lydian; A Aeolian has the same notes as C Ionian; and A Phrygian has the same notes as C Mixolydian.

But the red, blue, and cyan colors are all shuffled around when you go between the minor forms and their major counterparts. The three keys to learning this and being able to use it in improvisation are:

1. Always know where the tonal center of your scale is (the red notes) inside the pentatonic form.
2. Always know where the rest of the triad is (the blue notes) inside the pentatonic form.
3. Use the Hiding in Plain Sight (and Break Into the Box) method to access the characteristic notes of the related modes.
   

Finally…

Don’t forget that this methodology works equally well for the other four pentatonic forms!