The pentatonic scale is an abbreviated 5-tone scale comprised of the 1st, flatted 3rd, 4th, 5th, and flatted 7th tones of a major scale. Although a regular major scale has interesting names for its modes, like Locrian and Mixolydian, the pentatonic modes are only by number - 1 through 5.
This system of learning guitar is a series of positions that represent the successive modes of the minor pentatonic. By expressing the scales in this form, they are easily memorized and are frequently used to expand players' technical ability to translate between modes of a scale. This scale is especially useful in modern guitar because of its close similarity with the blues scale (blues scale - 1 3b 4 5b 5 7b, pentatonic - 1 3b 4 5 7b). Armed with the Circle of Fifths, the blues and jazz guitar riffs that people rock out to the most come very easily. Close similiarity between these scales and both the regular major scale and the melodic minor scale makes the minor pentatonic boxes a great way to fit into different a different "feel" and still have an easy way to move to different neck positions during improvisation.
There is always more than one way to play a mode. But this is a straightforward representation of the 5 modes of a minor pentatonic. The tones represent the 1st, 3b, 4, 5, 7b notes of the major scale with the same root for the first mode.
W = Whole step
H = Half step
Major scale:
F (W) G (W) A (H) Bb (W) C (W) D (W) E (H) F
Minor Pentatonic:
F (W+H) Ab (W) Bb (W) C (W+H) Eb (W) F
The special steps with W+H are what make a minor pentatonic "minor" like using the "minor" third... -- but they are a great bridge between majors and minors.
First mode:
Frets:
**1**|2***|3**|4***
---x-|----|---|---x--
---x-|----|---|---x--
---x-|----|--x|------
---x-|----|--x|------
---x-|----|--x|------
---x-|----|---|---x--
Notes:
**1**|2***|3**|4***
---F-|----|---|---Ab--
---C-|----|---|-- Eb--
---Ab|----|-Bb|------
---Eb|----|-F-|-----
---Bb|----|-C-|-----
---F-|----|---|---Ab-
Second mode:
Frets:
***3|**4*|**5|**6
----|--x-|---|--x--
----|--x-|---|--x--
---x|----|-x-|-----
---x|----|---|--x--
---x|----|---|--x--
----|--x-|---|--x--
Notes:
***3*|**4**|5**|*6**
-----|---Ab|---|--Bb--
-----|---Eb|---|--F--
---Bb|-----|-C-|-----
---F-|-----|---|-Ab--
---C-|-----|---|-Eb--
-----|--Ab-|---|-Bb--
Third mode:
(This one is a pain in the arse. I can never decide if it's better to play it starting with my middle finger or my index finger)
Frets:
**5**|*6**|7**|8***|*9**
-----|---x|---|---x|-----
-----|---x|---|----|--x--
---x-|----|---|---x|-----
-----|---x|---|---x|-----
-----|---x|---|---x|-----
-----|---x|---|---x|-----
Notes:
**5*|**6**|*7**|8**|*9**
----|---Bb|----|-C-|-----
----|---F-|----|---|--Ab
---C|-----|----|-Eb|-----
----|---Ab|----|-Bb|-----
----|---Eb|----|-F-|-----
----|---Bb|----|-C-|----
Fourth mode:
Frets:
***8*|*9**|10**|*11**
---x-|----|----|----x---
-----|---x|----|----x---
---x-|----|---x|--------
---x-|----|---x|--------
---x-|----|----|----x---
---x-|----|----|----x----
Notes:
***8*|*9**|10**|*11**
---C-|----|----|----Eb---
-----|--Ab|----|----Bb---
---Eb|----|---F|--------
---Bb|----|---C|--------
---F-|----|----|----Ab---
---C-|----|----|----Eb----
Fifth mode:
Frets:
**10*|**11*|*12*|*13**
-----|----x|----|----x---
-----|----x|----|----x---
---x-|-----|----|----x---
---x-|-----|----|----x---
-----|----x|----|----x---
-----|----x|----|----x---
Notes:
**10*|**11**|*12*|*13**
-----|----Eb|----|---F---
-----|----Bb|----|---C---
---F-|------|----|---Ab---
---C-|------|----|---Eb---
-----|----Ab|----|---Bb---
-----|----Eb|----|---F---
Rinse, and repeat. The most important thing to notice is that they are all the same notes. The whole idea is that a mode starts on a different note than the root, for easy transitions to other chords. This pattern of repeating notes within a progression also applies to diminished or augmented chord voicings; this is another great demonstration of why the minor pentatonic is very useful, if a tad bit overused
Because the pentatonic scale is a 5-tone scale, the patterns that they describe are a cut-down version of larger patterns in 6, 7, or 8-tone scales. These more generic patterns also show the benefits of the guitar's standard tuning structure, using the changing interval between the G and B strings to introduce a minor interval very easily into mechanically straightforward movements for the player. In these patterns shown, the fourth note of the scale is always the fifth of the root of that mode -- it is important to note that the fifth does not appear in these modes as either diminished or augmented. Example: for a C minor pentatonic, the fifth of C is A.
C Minor Pentatonic
-----------------------------
Notes: C Eb F A Bb
Intervals: 1 3b 4 5 7b
Modes: 1 2 3 4 5
For the second mode of the scale, starting on Eb, the fourth note is Bb. B-FLAT IS THE FIFTH OF THE E-FLAT MAJOR SCALE. It hasn't been adulterated so you are free to move around about these modes and change keys in the most common way that songs change keys. You can build up your whole career on this simple concept if you so choose... However, I would recommend learning some more spicy scales so that you can start letting 9ths, 11ths, and 13ths into your black little heart. There's always the major pentatonic modes, and all sorts of Exotic Scales.