## Unearthing the Structure

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Musenfreund
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### Unearthing the Structure

I read the lesson : http://www.guitarnoise.com/lessons/unea ... structure/ (understanding the structure) and there's a little thing that get me stucked bellow the subtitle: PROGRESSIVE THOUGHT...

I don't undertand the table and more specifically the Keys number (I-II-III-IV-V) and those other things:

Quote:
I - IV - V (the blues becomes rock and roll)
Okay, most of you are familiar with what is known as "twelve bar blues." This is the format used in the vast majority of blues songs. In a nutshell, the verse of a song (and it's usually all in verses) is twelve measures long. Each measure (marked by a "/") is four beats ("-") and follows this pattern:

I - - - / - - - - / - - - - / - - - - / IV - - - / - - - - /
I - - - / - - - - / V - - - / IV - - -/ I - - - / - - - -/

So if someone tells you that a song is twelve bar blues in A (as in "A"nother blues song!), you know that it will play out as follows:

A - - - / - - - - / - - - - / - - - - / D - - - / - - - - /
A - - - / - - - - / E - - - / D - - -/ A - - - / - - - -/

Maybe I have missed a lesson that explained those things, could you send me the link?

So my main question is: What does it means when I read in the table:

Key - I - II - III - IV - V
C - Dm - Em - F - G

What are the relations between C, Dm, Em, F and G?

Thanks!

Clau
Well we all shine on--like the moon and the stars and the sun.
-- John Lennon

Musenfreund
Guitari Lama
Posts: 8582
Joined: September 15th, 2002, 6:20 am
Location: Nutopia!
You might try looking at the lesson Before You Accuse Me. David explains the 12-bar structure there.

The second part of your question relates to a chord progression. In the example you listed, you're working with chords in the key of C.

You begin with the scale for a key. For C:

C D E F G A B C (each scale follows a pattern of steps, right? W = whole step, H= half step)

C w D w E h F w G w A w B h C

A chord progression takes that scale and using chords in the pattern:

major minor minor major major minor half-diminished seventh major creates a progression:

C Dm Em F G Am Bm7b5 C

That's why the chords are as they are where you listed them. The Blues, however, uses primarily the 1, 4, and 5 chords in the progression. In the key of C: C F and G.

I hope that made some sense!
Well we all shine on--like the moon and the stars and the sun.
-- John Lennon