Musical forms and structures: binary, ternary, rondo, sonata, variation, fugue and song forms
What this domain tests
You must label a structure with letters plus bar numbers, justify each boundary with a cadence or thematic event, and use the correct genre vocabulary (binari, ternari, rondó, sonata, variacions, fuga, lied).
Core schemes
- Binari (binari simple, AB) versus binari recompost (||: A :||: B A' :||), typical of Baroque dances and the minuet. The return of A is shortened or tonally adjusted, which is what separates it from ternary.
- Ternari (ABA): the middle section contrasts key and texture, and the da capo return is complete.
- Rondó (ABACA, with tornada and copla): the refrain returns in the tonic each time, episodes move away.
- Sonata: exposició (first theme in tonic, pont modulating, second theme in the dominant or, in minor, the relative major, closing theme) - desenvolupament (fragmentation, sequence, modulation) - reexposició (second theme now in tonic) - coda.
- Variació: tema amb variacions, plus ground-bass types (xacona, passacaglia).
- Fuga: subjecte, resposta (real if exact, tonal if adjusted), contrassubjecte, episodis, estret, pedal.
- Cançó: estrófica, AABA, tornada plus estrofa.
Worked example
A movement marked 3/4 opens with an eight-bar phrase ending on V (semicadència), repeats it, then a sixteen-bar section that touches the dominant and closes with a shortened return of the opening eight bars over a tonic pedal. Reasoning: the return is incomplete and the middle section ends without a full tonic close, so this is binari recompost, not ternary. If the return were complete and the middle section closed firmly in a contrasting key, ABA would be the better answer.
Traps that cost marks
- Calling any ABA "sonata form", or any AB "ternary".
- Ignoring repeats when counting sections.
- Labelling a fugue answer "real" when it is adjusted to stay in key (tonal).
- Missing that the recapitulation's second theme must be in the tonic - that key change is the whole point.
- Confusing rondo (ABACA) with sonata-rondo (ABACABA with a development).
- Naming a form without giving the bar numbers where sections begin.