This month we will take a step back in complexity and take a look at the Pentatonic scale. You form this scale by playing notes 1, 2, 3, 5 and 6 of the Major scale. The first thing you may notice is that this gives a more wide open, less linear sound than the Major scale, due to the 4 and 7 that have been dropped from the scale. This allows for using the scale in several different situations.
Start first by trying it over the chord of the same name. For instance, the G Pentatonic scale would be G, A, B, D and E. Try this over a G major chord to start. You may notice that this gives a country flavor to your solo, which is indeed how this is often used. There are rock players who will also use the scale in this manner, so try it and hear how it sounds. It will also work in a jazz context.
Next, try it over a G7 chord. If you look at the scale, you will notice that it contains a 9 and a 13 in relation to the dominant chord, so using this scale can "extend" your dominant chord, implying a G9 or G13 chord. Against a major seventh chord these would be a 6 and a 9, so this scale would also work against a G6, GMaj9, or a G6/9 chord. The important thing to note here is that with no seventh in the scale, you can use it over both major and dominant chords.
Another common usage involves the major/relative minor relationship. The relative minor is the sixth note of the Major scale. For example, note six of the Bb scale is G. The relative minor of Bb then, is Gm. Using this relationship, take the Pentatonic scale, in this case Bb, and first, play it over a G major chord. The notes in the scale would be G, Bb, C, D and F, (starting on the G rather than Bb). You will probably hear the rock/blues sound that this scale gives you, which is why it is favored by rock players. You often will hear this referred to as a rock/blues scale.
It should make sense that you can also use this scale over the Gm chord as well, especially since it contains the 3b of the Gm chord. Try it out and see how this sounds. Notice too that the scale contains the 7b and 9th, so Gm7 or Gm9 are good candidates for places you can use this scale also.
As with everything else we have gone over here, experiment. There is no absolute right and wrong. For instance, take each of the notes of a Chromatic scale, and try the Pentatonic scale built on that note against a dominant seventh chord. Analyze each note of the scale in relation to the chord. You may be surprised at some of the combinations that work. Try this with all the different chord types, major, minor and dominant.
Any type of scale can work in any style of music, depending on how you phrase your notes. By trying this scale in different styles, you can add a lot to your solos. The main thing is not to limit yourself and to try anything. The open nature of these scales allow them to function in a lot of different situations. Above all, have fun.