Watch the Up a Step: Further Extensions online guitar lesson by Kenny Wessel from Shades of Jazz
Another application for the minor pentatonic scale is to use it to extend the harmony over a minor seventh chord. We can use the simple minor pentatonic scale up a whole step from the chord's root to enrich the harmony of a minor chord. Normally using a blues scale built on the root of a minor seventh chord, we get mostly chord tones 1, b3, 5, b7 (and one extension - the 11th). But if we use a minor pentatonic built a step up from the root of our minor seventh chord, we get some hipper upper extensions. For instance, if we use a B minor pentatonic scale over an A minor 7 chord, we'll get the notes - B, D, E, F# and A. Relating those notes to the harmony - an A minor 7th chord, we get a 9, 11, 5, 13 and root. Now we have all three upper extensions of the minor seventh chord, which is more colorful than the very inside-sounding A minor pentatonic scale. This simple re-adjustment will spice up your lines, and open up your harmony a bit. We get a richer sound, it's a subtle difference, but will add some color to your minor 7ths!