How do you add simple chords to a melody so the harmony fits and the phrase ends well?
Harmonise a simple melody using the primary chords (I, IV, V), match chords to the melody notes, change chords at a sensible rate, and place a cadence at the phrase end
A clear, step-by-step answer to the N(A)-Level Music composing outcome on harmonising a tune. Using the primary chords I, IV and V, matching a chord to each melody note, choosing a sensible harmonic rhythm, and placing a perfect cadence at the end.
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What this dot point is asking
SEAB wants you to add simple chords to a given melody using the primary chords I, IV and V, matching a chord to the melody notes, changing chords at a sensible rate, and ending with a cadence. The big idea is that harmonising a tune is a step-by-step job: for each part of the melody you pick a chord that fits its notes, you do not change chords too often, and you finish with a strong cadence.
The answer
Step one: know your three chords
Most simple harmonisation uses just the three primary chords of the key. In C major they are I (C, E, G), IV (F, A, C) and V (G, B, D). Knowing the three notes of each chord is the foundation, because you will match the melody to them.
Step two: match a chord to the melody
For each main melody note (usually on the strong beat of each bar), choose a primary chord that contains that note. A melody note of E fits chord I; F fits chord IV; D fits chord V. The melody note should be one of the three notes of the chord you pick.
Step three: choose when a note fits more than one chord
Some notes belong to more than one primary chord (for example, C is in both I and IV; G is in both I and V). When this happens, pick the chord that gives the smoothest progression and suits the place in the phrase, often I at points of rest and V approaching a cadence.
Step four: set the harmonic rhythm and the cadence
Harmonic rhythm is how often the chords change. Change at a steady rate, usually about once per bar, not on every note (which sounds fussy). End the melody with a perfect cadence (V to I), so the phrase lands on the home chord and sounds finished.
Examples in context
Example 1. A hymn or carol. Hymns and carols are harmonised almost entirely with the primary chords I, IV and V, changing roughly once per line or bar, with a clear cadence at each phrase end. Working out the chords of a simple hymn is excellent practice.
Example 2. A three-chord folk or pop song. Countless folk and pop songs use only the tonic, subdominant and dominant of their key. Matching those three chords to the tune, and hearing the cadence at the end of each section, shows how far the primary chords stretch.
Try this
Q1. Name the three primary chords in C major and their notes. [2 marks]
- Cue. Chord I (C, E, G), chord IV (F, A, C) and chord V (G, B, D).
Q2. A melody note is F in C major; name a primary chord that fits it and explain why. [2 marks]
- Cue. Chord IV (F, A, C) fits, because the melody note F is one of the three notes of that chord.
Q3. Explain what harmonic rhythm is and why it should not be too fast. [3 marks]
- Cue. Harmonic rhythm is how often the chords change; if a new chord falls on every note the harmony becomes fussy and hard to follow, so a steady rate such as one chord per bar keeps it clear and musical.
Exam-style practice questions
Practice questions written in the style of SEAB exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Original8 marksYou are given a simple eight-bar melody in C major and asked to add chords using only the primary chords I, IV and V. Describe step by step how you would choose the chords and where you would place a cadence.Show worked answer →
List the chords and their notes. In C major: I = C, E, G; IV = F, A, C; V = G, B, D. These three primary chords can harmonise most simple tunes.
Match a chord to the melody. Look at the main melody note in each bar (or on each strong beat) and choose a primary chord that contains that note. For example, a melody note of E fits chord I (C, E, G); a melody note of F fits chord IV (F, A, C); a melody note of D fits chord V (G, B, D). Where a note fits more than one chord, pick the one that gives the smoothest progression.
Set a sensible harmonic rhythm. Change chords at a steady rate, often once per bar (or per strong beat for faster tunes), not on every single note.
Place the cadence. End the melody with a perfect cadence, chord V then chord I (G major to C major), landing on I as the last bar reaches the tonic, so the phrase sounds finished.
What markers reward: correct primary-chord notes, a method of matching a chord that contains the melody note, a steady harmonic rhythm (roughly one chord per bar), and a perfect cadence (V to I) at the end. The strongest answers mention choosing the smoothest option when a note fits more than one chord.
Original6 marks(a) Explain what is meant by harmonic rhythm and why it should not be too fast. (b) A melody note is G in C major; name two primary chords that could harmonise it and explain how you would choose. (c) State which two chords you would use for a perfect cadence and why.Show worked answer →
(a) Harmonic rhythm is the rate at which the chords change. It should not be too fast (a new chord on every note) because that makes the harmony fussy and hard to follow; a steady rate such as one chord per bar keeps it clear and musical.
(b) The note G is found in chord I (C, E, G) and in chord V (G, B, D). To choose, look at the surrounding chords and pick the one that makes the smoothest progression and fits the place in the phrase, for example use V if you are approaching a cadence, or I if it is a point of rest.
(c) A perfect cadence uses chord V then chord I. It is used because moving from the dominant to the tonic gives a strong, finished sound, landing on the home chord to close the phrase.
What markers reward: a clear definition of harmonic rhythm and why a very fast rate is bad, naming both I and V for the note G with a sensible way to choose between them, and the perfect cadence (V to I) with the reason it sounds finished. A strong answer links the choice to the position in the phrase.
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