A pentatonic scale consists of 5 notes (instead of 7 notes like a major scale). The fact that there are less notes gives it a more open sound. Its also great to sometimes only pick a few notes from a scale and try to make some interesting melodies using that subset of notes. The restricted number of notes is a nice way to focus on a smaller idea, rather than being overwhelmed with too many note choices.
For the blues I will focus initially on the minor pentatonic scale. This name refers to how the scale is constructed, which is based on the following intervals: minor 3rd, whole step, whole step, minor third. For E minor pentatonic this gives us E, G, A, B, and D.
So for an E blues progression this would give us the root (E), minor 3rd or #9(G), 4th (A), 5th (B), and minor 7th (D) over an E7 chord. For the IV chord which is A7, this gives us (relative to A), the root (A), 2nd (B), 4th (D), 5th (E) and minor 7th (G), and for the V chord which is B7, it gives us the root (B), minor 3rd or #9 (D), 4th m (E), minor 6th (G) and minor 7th (A).
As you may notice, some notes appear to be incorrect (such as G over E7 instead of G#) or some notes are missing (no C# played over the A7 chord). This is okay in blues (and jazz) - many blues and jazz masters have used this and in fact this is partially what gives the blues it's sound. Let your ears be your guide.
On the next pages, I show you a sequence, and a blues groove you can practice over.
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