Cadences in Grade 5 Music Theory: Perfect, Imperfect & Plagal

The last-two-chords method · 五級樂理終止式

A cadence is just how a musical phrase ends — and in ABRSM Grade 5 Theory you only need to tell apart three of them. Every cadence question comes down to the same move: look at the last two chords, and nothing else.

The three cadences at Grade 5

Cadence	Last two chords	How it feels
Perfect	V → I	Finished. A full stop.
Plagal	IV → I	Also finished — the "Amen" ending in hymns.
Imperfect	anything → V	Unfinished. A comma — the music must carry on.

A perfect cadence in D major: chord V (A major) to chord I (D major) — D major: the last two chords are V (A) → I (D) — a **perfect cadence**. The bass falling a 5th (or rising a 4th) is the giveaway.

A checklist that never fails

Find the key from the key signature (and check the end of the melody agrees).
Name the last chord. Ends on V → it's imperfect, done. Ends on I → go to step 3.
Name the second-to-last chord. V → perfect. IV → plagal.

Step 2 is where most marks are saved: both perfect and plagal end on chord I, so the second-to-last chord is the real question. Check the bass note first — it's usually the root.

How the exam actually asks it

Grade 5 papers don't ask "define a plagal cadence". They give you a short melody or a two-stave extract with the final chords shown (or labelled with boxes), and ask you to name the cadence — exactly like the figure above. That's why practising from notation beats memorising definitions: the skill being tested is reading, not vocabulary.

Ear check (if you play): perfect and plagal both sound finished, but perfect has the bass falling a 5th — the strongest possible ending. Plagal is softer, like "A-men". If you can hear the difference once at a piano, the paper version becomes much easier.

Common mistakes

Answering from the last chord alone. Ending on I doesn't decide perfect vs plagal — the chord before does.
Forgetting the key. Chord V in D major is A major; in G major it's D major. Same notes, different Roman numeral — always establish the key first.
Overthinking inversions. At Grade 5, cadence questions are about which chords, not which position they're in.

Practise with real exam-style questions

Tonica's Grade 5 mock papers include cadence questions in the real ABRSM format — notation first, instant marking, an explanation for every answer, in English and 中文. Paper 1 is completely free, no signup.

Try cadence questions free →
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