I was messing around with blues jam tracks on youtube, and have been applying the minor pentatonic scale to improvise a lead to the jam tracks. Works great! Once you learn the pattern, you can do it in any scale, pretty much all over the fretboard. The thing is, (for me anyway) playing to the jam tracks is a lot more fun that just repeating the scales back and forth. Try it!. I'd suggest finding a "slow blues in G" on youtube, then just goof around with the minor pentatonic scale while the jam track plays in the background. Once you get good with that, you can do "A" by shifting the pattern up 2 frets, or "C" by shifting up 5 frets, etc, using same scale pattern.