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A6. Harmonizing a Melody I

Grade 6 Music Theory: Lesson A6 Harmonizing a Melody I

In the grade 6 music theory exam, you have an optional question to harmonize a melody using Roman numeral notation (e.g. Va). (If you don't choose this question, you will need to do the question on creating a bass line using figured bass).

The question will look something like this:


Write chords at each place marked * to harmonize this melody.

Using Roman numerals, you need to suggest a chord and its inversion for each starred note. For example, you need to write "Va" for a root position dominant chord, not just "V". The starred note in the melody must be part of the chord you use to harmonize it.

There are many rules which you need to try to learn. In this lesson, we will explain how to tackle this question, and what those rules are.


1. Available Chords

In any key (major or minor), chords I, IV and V are the primary chords and II, III, and VI are secondary. Chord VII is so similar to chord V7 that it is not normally considered to be a chord in its own right, but a "V substitute".

Primary chords are essential for fixing the key of a piece. Chords I and V do this job together. Chord IV is not so important in this respect. For this reason, melodies should always begin with I and V. It is possible (but not recommended) to harmonize every single note of the melody using only the primary chords. Your melody should also end with a cadence formed from primary chords. Chord V is major in a minor key (e.g. E major in the key of A minor).

Secondary chords are essential for creating an interesting harmony. This is especially true in major keys, where the primary chords are all major. You will need to make sure that some secondary chords are used in your harmonization.

Chord III is rarely used. It is possible (but not recommended) to use it in a major key (where it is a minor chord, e.g. E minor in the key of C major). It is NOT possible to use an augmented III in a minor key, (e.g. C-E-G# in the key of A minor), but sometimes a major chord III is possible (because it’s the relative major chord).

This leaves us with the following chords. (Capitals=major, lower case=minor, °=diminished)

Major keys: I – ii – IV – V – vi – vii°

Minor keys: i – ii° – iv – V – VI – vii°


2. Available Inversions

Major and minor chords can be used freely in root position (root note in the bass) or first inversion (third of the triad in the bass). You should use a good mixture of root position and first inversion chords.

Second inversion chords (fifth of the triad in the bass) can only be used in a passing 6-4 or cadential 6-4. (See lesson A3).

Diminished chords (vii° in all keys and ii° in minor keys) can only be used in first inversion.

Cadences should be harmonized with root position chords. Cadences which occur in the middle of the piece are more flexible, but aim to use the root position chords if you can. Cadences which occur at the end of the piece should only use root position chords.

Root position chords are notated with a lower case "a", first inversions are "b", and second inversions are "c". So, "Ic" means a tonic chord in second inversion.
Vb is only available if the leading note is not in the melody. You cannot double the leading note.

Never use Va-vib. The bass notes of these two chords are the dominant and tonic. Our ears expect to hear chord I with the tonic bass note after V, so the vi chord sounds wrong. For example, in C major, the bass moves from G to C:



3. Repeating Chords

Change the chord with each starred melody note. Don't use the same chord twice (or more) in a row.

You can use the same chord in a different inversion, but only when moving from a strong to a weak beat.

For example, this harmonization is ok, because chord Ib falls on a strong beat, and Ia on a weak beat:


But in this example, chord Ib falls on a weak beat (2nd) and Ia falls on a strong beat (3rd), so it's not ok:



4. Consecutives

Consecutive perfect fifths and octaves are forbidden.

Check the interval made between the bass note and melody note. If it is a perfect fifth, you cannot follow it with another perfect fifth. The same goes for perfect octaves.

The following bar shows a poor choice of chords.


The first chord (Va) creates an interval of a perfect 5th with the melody, and so does the next chord (Ia). These are consecutive fifths. The third chord (IVa) creates a perfect octave with the melody, and so does the Ib chord which follows it. These are consecutive octaves.

Notice that here the intervals are actually compound fifths and octaves (i.e. more than an octave apart). This makes no difference: consecutive octaves and fifths are forbidden whether one or both of the intervals are compound or not. Diminished fifths do not cause consecutives when they are next to a perfect fifth, but you should avoid moving from a diminished 5th to a perfect 5th.

Note that repeated 5ths and octaves (e.g. C-G followed by another C-G) are perfectly acceptable.


5. Augmented Melodic Intervals

Augmented melodic intervals are forbidden.

Your bass line is automatically created when you choose the inversions of your chords. Check the notes in the bass line and make sure there are no augmented intervals. (An augmented interval is one semitone (half step) wider than a perfect or major interval.)

This choice of chords is poor. The bass line moves by an augmented 4th:



6. Cadences

Cadences are musical versions of punctuation. They signify a natural pause in the music. A comma is like an imperfect cadence – one which leads to chord V. We pause, but we are aware that more is going to come. A full stop (period) is like a perfect cadence (V-I). We are assured that an end has been reached.

Unlike in the grade 5 exam, cadences will not be pointed out to you. You need to work out where they are yourself.

Cadences occur at the end of a phrase. You can usually spot them because there is

• A longer note value than elsewhere in the melody

• A pause mark

• A double bar line

• A combination of the above

Aim to use root position chords at a cadence. Don't assume that the melody will end with a perfect cadence – sometimes you are given an incomplete melody, which might end with an imperfect cadence.

Plagal cadences (IV-I) are also possible, but they are not used as much as the perfect and imperfect cadences.


7. Common Progressions

Lesson A4 discusses the common progressions in detail.

Aim to use the most likely chords in every case. The most typical progressions are:


Major Keys

• vi – ii – V

• ii – V – I

• Ic – Va – Ia

• V – vi

• IV – I

Minor Keys

• VI – ii° – V

• ii° – V – i

• ic – Va – ia

• V – VI

• iv – I


In each of these progressions, with the exception of V-VI, the root (but not necessarily the bass) rises or falls by a fifth or fourth.

Here is an example.


The chords are via – iib – Va – Ia. The bass line falls by a third from E to C, rises a second to D, then falls a fifth to G. The fundamental bass is given below the stave. This shows the roots of each chord. Each root rises or falls a fifth or fourth.

You are not restricted to root movement of fourths and fifths, but this kind of movement creates the strongest, most stable bass line.

You can also move the root by step (V-VI is an example, or IV-V).

Root movement by a third is weak, because the two adjacent chords share two common notes. For example, if F major moves to A minor, both chords share the notes C and A. You can use root movement by a third, but use it very sparingly.

Chord I can be followed by any other chord.


8. Contrary Motion

Whenever possible, aim to have the melody and bass line move in contrary motion (opposite directions) from each other. It won't always be possible, but it should be your first choice.


How to Tackle the Harmonization Question

1. Work out the key (is it major or minor?)

2. Make a list of your available chords. Highlight the diminished chords, so that you remember to use them in first inversion.

3. Find the cadences. Complete these first with root position chords. Use a Ic-Va-Ia progression if you can. Chord iib is often a good choice before Ic.

4. Harmonize the first two (or possibly three) chords with I and V, to establish the key.

5. Harmonize the rest of the melody, using a good mix of primary and secondary chords and mixed inversions. Use common progressions where possible. Write in the bass line as you go along, and with each note you write, make the following checks with the previous chord:

• No consecutive perfect 5ths or octaves

• No augmented melodic intervals

• Chords are not repeated exactly

• Repeated chords with different inversions fall on strong-weak beats


When you are working out your answer, it is essential that you write in the notes of the bass line, as you go along. This is the only safe way to make sure that your harmony is "grammatically correct".

Write in the Roman numerals only when you have decided on your chords, then erase the bass line notes, so that you are left with the Roman numerals only. This is the way your exam paper should be handed in for marking.



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