Jazz Guitar Lesson

The Major Scale

The major scale is the single most important element in music. It's the most common musical "sound" we know (do re mi fa sol ...) and it's the main reference for all other musical materials (scales, chords, arpeggios, tunes, improvisations, etc.)

That scale has been around for centuries and is the "common ground" for all the music on earth,throughout history. For example, most lullabies, traditional melodies and national anthems are in the major scale...

...and still today, most of the pop/rock/jazz of the 20th and 21st centuries is based on the same scale! (in one way or another)

It's obvious that any aspiring jazz guitarist should eventually master the major scale. And, not only on the level of mere memorization but also on the hearing and tactile / technical levels.

On the Guitar

C D E F G A B C
[Notice open D, G and B strings]
Please refer to A Modern Method for Guitar

C D E F G A B C
[Notice the distance between E-F and B-C]
Please refer to The Advancing Guitarist

Hearing It by Singing It

Also, it is highly common for jazz guitarists to sing along to their playing. Try it! It helps reinforce the link between your fingers (what you play) and your ears (what you hear inside.)

This basic scale is so easy to hear and recognize that it is worth trying right now! Sing it.

In Position

It is a very good way to "compartmentalize" the neck. You will get familiar with the whole instrument dealing with it chunk by chunk.

This is the "2nd position" because the index
finger of the fretting hand is aligned with
the second fret... I like to call it the
5-2 position in my articles on position playing.

Here's a series of articles I wrote on Positions :
       
-1- How to Have Six Fingers and Control the Universe
-2- Top Must-Know Positions for Jazz Guitar
-3- Scales Polishing and Connecting

...psssst...

The scales can also be played in a "diagonal" way on the guitar. (but don't tell anyone!)

Theory : Scale Construction

For example, C major scale :

The half-steps are between the third-fourth and seventh-first degrees of the scale (E-F and B-C in the case of C major.)

Look at the single-string version above for frets 5-6 and 11-12.

The placement of those half-steps in two specific location creates this scale's unique sound characteristics.

Looking at a piano keyboard also clear things up for me :
(there's no black key between E-F and B-C)

THE Reference

The major scale is the point of reference for building other scales with a different sound. The numbers 1 2 3 4 5 6 7 are the major scale degree. 

We alter the major scale degree with flats (b = half-step lower) and sharps (# = half-step higher) in order to get different scales.

For example :

Melodic Minor Scale Formula : 1 2 b3 4 5 6 7
Harmonic Minor Scale Formula : 1 2 b3 4 5 b6 7
Mixolydian Mode : 1 2 3 4 5 6 b7
Dorian Mode : 1 2 b3 4 5 6 b7
etc.

...feeehhweew... ok that's all for the theory!

This Wikipedia article may explain it better than me...