as mentioned above, a sonata form is laid out in three general sections: exposition, development, and recapitulation. the exposition and the recapitulation will each include a primary theme or theme group (P), a transition (T) that produces great energy and modulates to a secondary key, a secondary theme or theme group (S) in the new key, and a closing section (K) that may be thematic, but normally functions as an extended cadential passage. (can you use the 'third theme' for this?)
developmental techniques can occur anywhere in the form, but they are most commonly associated with the mid-section or development area. the development will conclude with a retransition area (RT) that will lead back to the tonic for the beginning of the recapitulation. unlike the exposition, in the recapitulation BOTH the primary theme (P) and the secondary theme (S) are found in the tonic key.