Chords in Grade 5 Music Theory: Roman Numerals & Positions

I, IV, V — and what a, b and c actually mean · 五級樂理和弦

Grade 5 chord questions centre on the three primary triads — tonic (I), subdominant (IV) and dominant (V) — and their positions. Two skills solve everything: naming which chord it is, and naming which note is at the bottom.

Step 1 — Which chord? Stack it in thirds

Rearrange the three notes (mentally) into a stack of thirds — the note at the bottom of that stack is the root. Then ask which scale degree the root is in the current key: degree 1 → chord I, degree 4 → IV, degree 5 → V. In D major, a chord built of A–C♯–E has root A = the 5th degree = chord V.

Step 2 — Which position? Look at the bass

Label	Name	Bass note
a	Root position	The root itself
b	First inversion	The 3rd of the chord
c	Second inversion	The 5th of the chord

So Ic means the tonic chord with its 5th in the bass; IVb is the subdominant with its 3rd in the bass. The position depends only on the lowest note — how the upper notes are spaced or doubled changes nothing.

Writing convention: at Grade 5 the Roman numerals stay UPPERCASE even in minor keys — Ic, IVb, Va. (Lowercase numerals for minor chords appear in other traditions, but not in ABRSM answers at this grade.)

How the exam asks it

You won't be shown one chord in isolation and asked to name it. The paper gives a short passage with chords marked by labelled boxes (X, Y, Z or numbers) and asks you to identify each as I, IV or V — sometimes with position, sometimes without. Work each box the same way: key first, root second, bass note third.

The very last box in a passage is often part of a cadence — if boxes Y and Z are the final two chords, naming them usually answers a cadence question at the same time. The two topics are one skill.

Common mistakes

Reading the bottom note as the root. The bass note tells you the position; the root comes from stacking thirds. In first inversion they're different notes — that's the whole point.
Forgetting the key. The same three notes are chord V in D major and chord I in A major. Establish the key from the key signature before naming anything.
Ignoring doubled notes. Four-note chords in two staves still contain only three different pitches — one is doubled. Identify the three, then proceed as usual.

Practise with real exam-style questions

Tonica's mock papers use the real labelled-box format for chord and cadence questions, with instant marking and an explanation for every answer, in English and 中文. Paper 1 is completely free, no signup.

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