This past semester, I took Music Theory III with Professor Michael Puri. For our final project, we had the option of either choosing a piece and writing an analysis paper or writing a fairly substantial model composition. I didn’t even think about it, as my choice was obvious. I elected to write a composition, and I chose to do my best at writing the exposition section of a piano sonata. We spent a lot of the semester working with this format, mostly using Mozart’s work as examples, so I felt fairly comfortable with it. Here’s a break down of sorts. It will be slightly technical and explained in theory language, so try to get past that.
The first four measures hold a sort of fanfare with both hands in unison. This serves the purpose of literally just getting the piece going and propelling it into the next section, which is the primary tonal and thematic section of the exposition (P section). This section does not last long, as it only spans across one eight measure phrase. Immediately afterward, I began experimenting with some modal mixture to start the transition section (TR) by transitioning into the parallel minor (D minor) whilst keeping similar thematic texture. This phrase only lasts half as long as the P phrase, as it leads to a cadence on the dominant chord and launches into a harmonic sequence characterized by a descending circle of fifths with diatonic sevenths. The left hand begins playing sixteenth notes, giving the TR section the increased texture that it is supposed to have. Everything eventually leads to a very big cadence (the medial caesura) on the dominant chord, tonicizing it and preparing the following section, in which the piece finds itself in the key of A major.
The secondary tonal and thematic area (S) begins at this point and proceeds forward in A. The texture is noticeably different, as it is quieter and utilizes more dotted rhythms. The section begins with a sentence phrase, the second of half which is an ascending stepwise harmonic sequence leading to an avoided cadence. The biggest part of the piece follows. It is a long, drawn out descending circle of fifths sequence ending in a big perfect authentic cadence (I would classify this as the essential expositional closure – EEC). What follows is some repetition of sections with things like avoided cadences and deceptive cadences thrown in until the repetition of the EEC phrase. We then come to the coda and the end of the exposition!
Sorry for that long, technical explanation. Don’t feel obligated to read it. Just listen :).