The three parts
- Exposition: first theme in the tonic; a modulating transition; second theme in the dominant key (in major) or the relative major (in minor); closing codetta. Usually repeated.
- Development: fragmentation and transformation of the themes, sequences, distant keys; ends with a retransition over a dominant pedal.
- Recapitulation: both themes return, now both in the tonic; the transition is altered so it does not modulate. Possible coda.
Tonal plan
- In C major: Exposition C → G | Wandering development | Recapitulation C → C.
- In A minor: Exposition A minor → C major | Development | Recapitulation A minor → A minor (or A major).
The logic
It is a drama of tonal tension: the second theme “away from home” creates a conflict that the recapitulation resolves by bringing it back to the tonic. Bernstein, in the Young People's Concerts, explains it as a magnet: the tonic pushes the music away and then pulls it back.
Lesson for the producer
- Present your materials (hook, riff) early.
- Develop: take the riff apart in the bridge, change the harmony, filter, fragment.
- Prepare the return with a dominant pedal (build-up).
- Return with impact: the final drop in the tonic is a recapitulation.
Real-world example
Mozart's Piano Sonata K. 545 in C major (1788): the exposition goes from C to G; the recapitulation, unusually, begins in F major before returning to C. It is one of the most commonly used examples of sonata form in teaching.