A classical minuet movement typically contains a main minuet, followed by a trio, _followed by a _da capo repeat of the main minuet (usually performed without taking the repeats). The movement, then, has a large-scale ABA’ form: minuet–trio–minuet da capo.
Both the main minuet and the trio tend to be small ternary structures. Like the minuet/trio movement itself, the small ternary form follows an ABA’ structure. However, the small ternary structure found in the typical main minuet is of the rounded binary type. That is, while there are three distinct modules—A, B, and A’—they are grouped into two larger sections, each of which is repeated.
The first part in the two-part structure is the first reprise, and the second part is the second reprise, so called because they each repeat. The first reprise contains the A module of the minuet; the second contains the B and the A’ modules.
Each section of the minuet’s (or the trio’s) small ternary form has its own formal function attached to it. The formal function exhibited in the A section is called exposition function; the B section contrasting middle function ; and the A’ section recapitulation function.
At the least, the exposition module of the minuet typically contains a primary theme: tight-knit (period, sentence, or hybrid), ending with a PAC, or occasionally a HC. It is common, however, for an exposition to have more complex structure, projecting not just primary theme, but secondary thematic function, transition, and closing. Not all of these functions are necessarily present.
Expositions always have a primary themes. A prototypical primary theme is (1) tight-knit and (2) ends with a PAC or HC in the tonic key. When an exposition does not modulate, it is understood to exclusively express primary theme function.
But if the exposition modulates, the functions of transition, and secondary theme may appear as well. At minimum a secondary theme will close with cadential confirmation (usually a PAC) of the subordinate key. Often, it is looser than the main theme—perhaps expanded or contracted.
If a phrase contains a [pivot chord modulation][modulation.html] linking the main key to the subordinate key, that phrase is understood to express transition function. (If a new phrase begins immediately in the subordinate key through [direct modulation][modulation.html], there is no transition function.)
Very, very often the transition and the secondary theme are “fused” together (TR==>S) in a single phrase.
Sometimes the secondary theme closes with a PAC and is followed by a closing section.
A contrasting middle section is significantly looser than the exposition. Though it may contain some kind of thematic structure (sentence, primarily), it often does not. Sequences and remote tonal areas are quite typical of the digression section. When doing analysis, your goal should be to identify the melodic/motivic material and understand the tonal structure.
Contrasting middle passages end with a I:HC, creating a harmonic interruption. Commonly, the I:HC is followed by a post-cadential “[standing on the dominant][externalExpansions.html].”
The definitive characteristics of a minuet’s recapitulation function are (1) the return of the basic idea from the A section at its beginning, (2) the return of the home key at its beginning, and (3) a final PAC in the home key.
A recapitulation typically copies the thematic and phrase-structural features of the exposition, but altering the secondary theme so as to end in tonic. Commonly, the recapitulation expands the exposition’s closing phrase.
Like the minuet, a trio is typically a rounded or simple binary form. It’s primary job is to establish melodic and harmonic contrast. While contrasting tonally with the main minuet is a central feature of the Trio, Trio’s often simply projection modal contrast. When the tonic stays the same, a major-key main minuet might be contrasted with a Trio marked minore. (The corresponding situation for a minor-key main minuet is a maggiore Trio.)