I was thinking of posting a quick tutorial of modes on a news update that mentioned them but didn't explain them, but then I thought better of myself as I'm not rock solid in the area. I figured I'd post what I came up with here and get some corrections and critiquing of my own understanding. Any help would be great.

Most descriptions of modes are fairly reliant on knowledge of a Major Scale. The Major Scale is simply a set of 8 notes with a specific interval between each note. The order of these intervals is w-w-h-w-w-w-h, with "w" being a whole step, and "h" being a half step. A C Major scale contains no flats or sharps because there is a whole step between each natural note except for B-C and E-F, which have half steps. These notes happen to be located at the 7th-8th scale degrees and 3rd-4th scale degrees, respectively, resulting in a scale with no flats or sharps.

Modes can basically be thought of as augmenting an Major scale or starting an alternate Major scale from a different scale degree, based on the name of the mode. Running a D Dorian scale is basically playing a C Major scale going from D to D instead of C to C. Alternatively you can memorize the differences in all the modes alternatively. D Dorian is a D Major scale with a flat 3rd and 7th degree (in this case, F and C). An interesting example is the Aeolian mode which is also known as a natural minor scale-both having a flat 3, 6, and 7 degree. You could think of playing this mode/scale this way, or by thinking of it as playing a C major scale starting from A since A is the 6th degree of the C scale.

An important note is that D Dorian, E Phrygian, etc are all diatonic to C Ionian, or Major, but only because they happen to be the second and third degrees of the C Ionian mode. E Dorian, for example, can be thought of as playing an E Major scale with a flat 3 and 7, or as playing an 8 note scale in the key of D Major starting from E, the second degree.

Degree started from: (think of the mode name as this scale degree of a Major Scale)

Ionian-1
Dorian-2
Phrygian-3
Lydian-4
Mixolydian-5
Aeolian-6
Locrian-7

Augmentations to Major Scale: (think of a Major Scale of the mode's name, but with these augmentations)

Ionian-Major
Dorian-flat 3, 7
Phrygian-flat 2, 3, 6, 7
Lydian-sharp 4
Mixolydian-flat 7
Aeolian-flat 3, 6, 7 (also Natural Minor)
Locrian-flat 2, 3, 5, 6, 7
Last edited by nanaki2007 at Dec 2, 2009,
yeah, pretty much. you've covered everything basic.

maybe throw in a detailed (but short) explanation of the major scale so people (theory n00bs) can see just how the alterations are made from the major scale.
added a description of a major scale. i feel like i should say that nth scale degree is just the nth note of the scale but i don't know where to put it...
I would include examples of where they can be found in popular music. Eg: The stairway to heaven solo uses the aeolian mode, santana uses the dorian mode in a lot of his music, the simpsons theme song is written in the lydian mode etc etc.

In any case, you're likely to get more constructive criticism over in the musician talk forum.
thanks, i'll try it there too