Pentatonic scales consist of five notes. The term Pentatonic comes from Penta- meaning, Five and tonic, meaning, Tone, or Note. Pentatonic scales are commonly used in blues and rock lead guitar. You might be wondering why pentatonic scales are used at all, when taking into consideration that the scale from which they are derived, consists of seven notes- only two more notes than the pentatonic scale. Why not just use the major scale?

First, lets take a look at a scale, C Major, consisting of; C, D, E, F, G, A, B and C. The relative minor of C Major is A Minor, which consists of the exact same notes, but starts on the A note; A, B, C, D, E, F, G and A. Relative minors are the same scales as their major counterparts; the only difference is that they begin on a different note! The sixth tone is the most commonly used minor chord when playing in major scales, if you were to be playing in G major, E Minor is most commonly used.

To construct a pentatonic scale, start on the A note of the C major scale, and remove the second tone (B) and the sixth tone (F). The remaining notes are A, C, D, E and G. The reason for removing the second and sixth tone is to remove the half-steps from the scale. By removing half-steps from the scale, the pattern becomes movable, to the three minor chord positions of a major scale.

There are three minor chords that exist in the key of C Major, and those are D Minor, E Minor, and A Minor. Transposing the same note-pattern from an A Minor pentatonic to a D Minor, results in a scale that consists of; D, F, G, A and C. When playing these notes on the 10th fret (D), the D minor pentatonic is the same fingering pattern as the A minor, and can be used when playing in the Key of C Major. If you were to move the same fingering pattern to the 12th fret (E), the scale becomes E Minor Pentatonic- also be valid in the key of C Major. Essentially, the half-steps are removed all of these scenarios, but different notes are eliminated in each position to achieve the same goal.

The two keys most similar to C major are F Major and G Major, the F having one flat (Bb) and the G having one sharp (F#). The valid minor pentatonic scales in the key of F Major are G Minor, A Minor and D Minor. Compare these positions to the C Major, and you will see that they share two minor pentatonic patterns (D Minor and A Minor). Now, lets take a look at the valid pentatonic patterns in the key of G Major, which are; A Minor, B Minor and E Minor. The Keys of C Major and G Major share an A Minor pentatonic and the E Minor Pentatonic. When moving around the circle of fifths, every key shares two minor pentatonic scales with its neighboring key. Moving clockwise, the next key shares the third and the sixth minor chords; moving counterclockwise, the next key shares the second and sixth minor chords.

Although lacking two important notes, and appearing to be at a disadvantage in harmony, pentatonic scales are very flexible. And, if you were to combine the notes from the three minor pentatonic scales of a major key, you would have all seven notes that comprise the original major scale from which the pentatonic scales were derived. So, despite their somewhat keyless ambiguity, minor pentatonic scales in combination not only define their key, but also remain movable to other keys as well.

Pentatonic scales are a useful tool for learning the fretboard and keys. Whence you have memorized the fretboard, you will no longer rely on patterns or positions because you will see the fretboard as a collective whole.