Bach: Minuet, Notebook for Anna Magdalen a Bach (1725)
This piece is rather short in material, but is lengthened by the repeat bars at the end of each section. It very clearly begins in the key of G major. This first section is made up of four measure phrases. There is an IAC in measure four, which is the first occurrence of a cadence. Then in measure eight the first period is ended with a HC. The second period has another IAC at the mid-point in measure twelve, and then ends with the strongest cadence yet, the PAC in measure sixteen. Because both periods are eight measures long and are extremely similar in their musical content, it would be labeled as a symmetrical, and parallel double period.
Once we enter our new section we are in a different key. It is a pretty subtle change because it modulates to the dominant, which is D major. The first phrase, measures seventeen to twenty-one, ends in a HC. The period continues on with another four measure phrase that ends the period with a PAC (m. 24) in the key of D major. The last note in the bass clef of measure twenty-four (C natural) is a passing tone that leads us back into the original key of G major. The last period is symmetrical with all the others, containing two phrases both made up of four measures each. The first phrase ends on a HC in measure twenty-eight, and then the song is finished off with, of course, a PAC!!! This last section because of the key change between periods and the dissimilarity in the musical content would be considered a contrasting double period with symmetrical periods.