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Writing Chords to Accompany a Melody

The first question in the ABRSM grade 6 theory paper asks you to provide a chord progression for a given melody. You are given a choice of methods – writing Roman numerals, writing notes on the stave, or another method of your choice, (for example chord symbols or figured bass).

Most people choose to write Roman numerals for this question, and I think this is the best option. (This is because writing notes on the stave is a more difficult task with more room for error, and writing chord symbols does not let you see the functional chord progressions so easily).

The question is designed to test your knowledge of key, chords, inversions, progressions, cadences, voice leading, doubling, consecutives and decoration. All of these things are covered in earlier lessons, so do check back on those lessons if necessary.

You need to provide a Roman numeral (using the correct capitalisation), and also show the inversion of the chord, typically with the letters a, b and c.

Here is an example question.

ABRSM grade 6 Q1a Harmonisation example question
Watch a video demo of how to get started on this question here…

You need to write a chord at each asterisk.

Every note in the melody must be either a chord note in the chord you have chosen, or a recognised type of melodic decoration. There will normally be two cadences – one at the end, and one roughly in the middle. The note values at a cadence are usually longer than those used elsewhere (if the middle cadence is difficult to spot, look at bars 3-4 as this is the usual location).

It is essential that you pencil in the bass notes on the stave as you go along. This is so you can easily spot consecutive 5ths/8ves and also poor voice leading such as augmented 2nds. The bass line should then be rubbed out before you hand in your exam paper.

First work out the key, by checking for the leading note of the minor key. This melody is in G minor, because the melody includes F#.

You may find it helpful to write out the 7 triads of the key. We do not normally need III+ (augmented mediant), or any of the other triads from the melodic minor scale.

The most common triads in G minor are I (G-Bb-D), ii° (A-C-Eb), III (Bb-D-F), iv (C-Eb-G), V (D-F#-A), VI (Eb-G-Bb) and vii° (F#-A-C).

For each melody note, work out which chords the note belongs to. The horizontal lines show you how long each chord lasts for. Additional melody notes which are a step away will normally be decoration notes, whereas additional notes which are a leap away must be part of the same chord.

ABRSM grade 6 Q1a Harmonisation example question

E.g. Bar 1, beat 1, the A quaver (8th note) is a passing note, because it is a step away from chord note Bb. Bar 1, beat 3, the D crotchet (quarter note) is a chord note, because it is a leap from A.

If the melody note(s) fit more than one chord, choose the chord which makes the best progression. Aim to use primary chords (I, V, IV) in bar 1, and to use root position chords at cadences, if possible.  Avoid using the same chord across the bar line.

After choosing the best chord, work through the possible inversions of that chord. You need to consider the voice leading to/from that bass note (avoid dissonant bass line movement), check for any consecutives with the melody part, avoid doubling the 3rd in bass and soprano too much, and avoid moving into a first inversion chord by a leap. Second inversion chords can be used in the passing 6/4 or cadential 6/4 progression.

Where the melody moves up or down by a third, it is often a good idea to move in the opposite direction in the bass (with the same notes). The progression IVa-Vc-VIb (passing 6/4) often works well. Chord Ib is often better than Ia mid-phrase (Ia is better at a cadence). Avoid any progression which creates repeated bass notes (except Ic-Va, which is fine).

If you reach a point in the exercise where several chords seem to work ok, try working backwards from a cadence instead.

Try to use a good variety of chords and inversions.

Here are the steps summarised:

  1. Work out the chords for the key.
  2. Find the chords that fit each melody chord note.
  3. Check which notes are melodic decoration.
  4. Choose the best inversion.

Here is an example answer. I have included the bass line notes for reference, but these should be erased in an exam!)

example answer

Things to check for:

  • Make sure each chord includes any auxiliary harmony notes from the melody part.
  • Make sure you have used allowable progressions.
  • Make sure you have moved into suitable inversions.
  • Make sure you have standard cadences.
  • Make sure any leading notes or 7ths in the bass resolve correctly.
  • Make sure you have avoided consecutives.
  • Make sure you have avoided augmented 2nds in the bass line.
  • Make sure you bass line avoids repeated notes apart from Ic-Va).
  • Make sure you have used a good variety of chords.

ABRSM Grade 6 Q1a Practice Exercises

Click here to download a free PDF with exercises!