Lesson 1: Chords and Keys

Prior Knowledge: You cannot create harmony without a working knowledge of chords and keys, so we’ll begin there but you should be able to:

• Write out a circle of 5ths.
• Identify a key signature using the circle of 5ths.
• Write out the major or minor scale of a particular key.

Content of Lesson: Basic background of the knowledge required from scales, chords and keys. Only the basics will be covered in this lesson, and while no harmonising will take place the music theory discussed here must be understood before moving on.

Chords

If you are not confident using scales, I would strongly advice going over your scales theory before continuing. I will assume you can confidently use scales.

Chords can be easily constructed out of scales. There are three intervals that build a chord:

In a standard triad, there will always be a 3^rd and a 5^th above the root creating a major or minor chord. The 5^th is always perfect, except in diminished chords, which we will cover later. Other types of chord can be created but are not common in chorales.

In each key, seven standard triads can be created, for example in C major:

Roman numerals are always used to label these chords, based around the scale degree of their root note. In standard practice, upper case letters are used to identify major chords, and lower case for minor chords.

Primary and Secondary Chords

Six of these seven chords can be grouped into two categories: Primary Chords and Secondary Chords. In any particular key:

• Primary Chords: I, IV and V.
  Follows mode of the key. In a major key, always major. In a minor key, always minor.  
• Secondary Chords: ii, iii, and vi
  Always opposite in mode to the key. In a major key, they are all minor. In a minor key, ii is diminished but III and VI are both major. 

Chord vii is always diminished and requires special treatment, which we will look at later.

Chord Inversions: 

Inversions are simply chords with different notes in the bass. C major would normally have a C in the bass, but an inversion of C could have E or G in the bass instead. This gives us much more flexibility for bass parts.

To explain further, if a chord is written…

• with its root in the bass, it is in root position (written as ‘a’)
• With the 3^rd in the bass, it is in first inversion (written as ‘b’).
• With the 5^th in the bass, it is in second inversion (written as ‘c’)

The inversions can be identified by extending our chord table from before:

Using this table, and in the key of C major, we can see that a chord Ib would look like this, with the 3^rd in the bass:

While a chord Vc could be written as follows, with the 5^th in the bass:

Chords Practice Task: 

1. Write out a chord table (including inversions) for G major and F major.
2. In each key, write out in stave notation the chords Ib, IVa, Vb, VIIc, iib.

Keys

It is all very well being able to write out or play major/minor scales and chords in particular keys, but for harmonising chorales you will also need to understand the relationship between keys.

Chorale melodies will typically modulate several times through many keys. This is one of the reasons they are so well known for being a really good foundation for anyone studying harmony. They will usually begin and end in the same key, however the modulations are restricted to only closely related keys. That is to say the tonic (I), subdominant (IV), dominant (V) and the relative minors/majors of those keys.

A key relationship diagram is invaluable in both explaining the theory here, and also for when you come to harmonise your melodies. By writing out one of these, you can see exactly what modulations are possible and limit your choice of keys to the “correct” options.

Begin with the tonic in the centre. To the left, write the subdominant key and to the right the dominant. Underneath these, write the relative minors/majors for each. The example below uses C major as the tonic key.

Using this diagram allows us to identify paths through the different keys, for example if you know the second section is in F, and the third is in Em, you must move through other keys to get there, so perhaps F -> C -> G -> Em may work. The smoothest way to modulate will be to follow the lines in this diagram, although of course there are other ways to go about it.

Modulation will be covered in a separate lesson, but it is important before going further to be able to write out the chords/inversions tables for each of the six keys in a key relationship diagram.

Keys Practice Task: 

1. Write out a key relationship diagram for E major.
2. Write out a key relationship diagram for A minor.
   Remember that if you use a minor tonic key, your relative keys will be major.

Summary

You should now be able to:

1. Understand, identify and write out scales for all keys in the circle of 5ths.
2. Understand and be able to create chord tables for particular keys, including inversions.
3. Be able to write out chords and inversions from given roman numerals and inversions (i.e Ia, IV, VIIb, Vc).
4. Understand and be able to create a key relationship diagram for any given tonic key.

When you can do this, you are ready for Lesson 2: Rules of Chorale Harmony.