Crazyguy is totally right. Just learning music theory is useless unless you know how to apply it and can use it to create your own songs and riffs. If you are taking lessons, your teacher should be incorporating songs into your lesson material which are at your playing level and that go along with the theory that you are learning. If that's not the case, you should look for another teacher. Plus, you should be careful not to get too bogged down in music theory. Many music theory books focus on information, scales, chords, arpeggios, etc..., which may have some theoretical value but may be practically useless from a playing standpoint.

As for your theory question, if you play an A minor Pentatonic starting on the note, C, you are actually playing C major pentatonic, not C Dorian. Both A minor pentatonic and C Major Pentatonic are derived from the C Major Scale.

C Major Scale: C, D, E, F, G, A, B, C

C Maj. Pent.: C, D, E, G, A, C

A min. Pent.: A, C, D, E, G, A

The Dorian mode is also derived from the major scale, not the pentatonic scales. So in the above example, the Dorian mode (which starts on the 2nd tone of the MAJOR scale) would be D Dorian. (D, E, F, G, A, B, C, D).

The A# / Bb Major Scale would have no bearing to the above example. However, C Dorian would be the Dorian mode for the Bb Major Scale. (It would actually be B# Dorian if you were referring to the scale as the A# Major Scale -- but this little point is an example of theory which, while technically true, is practically useless from a playing standpoint in my opinion.)

I like to look at the Major scale as the root of all scales, chords, arpeggios, etc. (keep in mind, other people have other theories) That way I have a reference point to build all the scales, chords, arpeggios that I use when I play. It makes playing and adding new concepts and riffs much easier for me.

[Edited by trebledamage on 12-11-2001 at 10:48 AM]