The piece starts in A major.
Measures 1-8 form a parallel, symmetrical, expository period. There is an IAC in measures 2 and 6 and half cadences in measures 4 and 8.
There is a modulation to the dominant key of E major. Measures 9-12 make a symmetrical contrasting period with a half cadence at measure 10 and an IAC at m. 12. This period can evaluated as the transitory period.
Measures 12-20 is a repeating phrase with a PAC at measure 20. This is the developmental period and is back in the original key of A major.
Measures 20-29 is a parallel period with a cadential extension (m. 28-29). There is an IAC in m. 24 and again in m. 29. The cadential extension of only a measure simply reinforces the fact that this period is the terminative.