Lesson 7 - chord progression I

We talked a lot about chords in last chapters. Now we look at interconnectivity of chords in songs. Trust me or not, but most of songs consist of up to six chords. Of course I do not mean specific chords (absolute) as for example G7, but relative chord, for example tonic or subdomimant. Maybe you have never heard these names. In a guitar language are used roman numbers for it. Look here:

But names aren’t important. It is necessary to know, according to rules of harmony, that I, IV, V are major chords and II, III, VI are minor. But where lay these chords? It's easy. The tonic is first and it's up to you where you start. If the tonic will be C chord, then the whole song will be in a key of C. If you want to play a song in a key of A, then the A chord has to be the tonic (I). Following chords are moved by specific number of semitones (frets). Look here:

So in the key of C it will be:

In the key of A it will be:

Maybe you want to know how to find out in what key is a song you want to learn. There are more possibilities. The easiest way is to look at key signature of a song. I.e. how many of '#' or 'b' are placed in the beginning of a staff. Then you will need this table:

But sometimes you do not see any note staff. So there is a posibility to find out a key of a song from used chords. You know, that two minor chords side by side have numbers II and III (e.g. Dm (Dm7) and Em (Em7) are in the key of C) and that two major chords side by side have numbers IV and V (F (Fmaj7) and G (G7) are in the key of C). Find them and you can determine 'I' - key of a song… This table should by helpful. There are most used keys and used chords in them:

But it is not important to know key of the song, but which number you are playing (I, II, etc.). Nevertheless the above mentioned approaches will help to do this. But there is another way to recognize which chord is played. It is possible to do this only by ear. But it is very hard to learn such skill.

Sometimes a song is not strictly according to rules of harmony and I, IV or V is minor or II, III or VI is major. In this case, it is marked by 'x' before number. For example, when in the key of C is minor subdominant, write it down as xIV.

Using of these numbers has great benefits:

• Firstly, you will be independent of a song key (tonic is always I, dominant is always V, in any key).
• Secondly, learn 6 chords corresponding to numbers I, II, III, IV, V, VI and you can play almost every song.
• Thirdly, when you know any-fret chords, you can easily transpose any song. E.g. some song is in the key of G so you will play I (tonic) as major E variant chord on the 3rd fret. But if you will find out, that the song is too low for singing, you transpose it to the key of A - only move your hand two frets up and play it with the same chord variants...

Another great thing is chords substitution. It is handy especially when you are a second guitarist. You can play chord I over VI, chord IV over II and chord V over III. So you need to learn only three major chords I, IV, V and play them over a whole song.

If you want to understand why, look at the tone names (A, C, E, G), which are in chords VI and I. For example in the key of C:

As you can see, chords I and VI has two indentical tones (C and E). Moreover tone G is interval b7 in IV. So I chord is actually VI min7 chord without root tone (1). In the same way you can play IV over II and V over III.

Exercises for this lesson:

Now try to rewrite some song from chords to roman numbers. E.g. song is in the key of C and there are chords C, Em, Fmaj7 and G7. Then simply write I, III, IV and V beside names of chords. You will need it later...

Next: Lesson 8 - chord progression II

Other lessons:

Lesson 1 - first steps

Lesson 2 - intervals

Lesson 3 - tones

Lesson 4 - first chords

Lesson 5 - seventh chords

Lesson 6 - any-fret chords

Lesson 8 - chord progression II

Lesson 9 - arpeggios

Lesson 10 - scales