small ternary Form

Hi Nik,
I’m not Jon, but I think I can offer some insight into your need for structure in the small ternary form. The form is broken down into 3 parts, which get their origin from being scaled down from a larger, Sonata Form. These three parts are the Exposition, which is notated with an “A”, the Contrasting Middle “B” and the Recapitulation “A'”. From here I’ll break it down further.
The Exposition (A)
The exposition can either be a Sentence or a Period. To start out, I would use a period because the strong cadence at the end of the phrase really helps to define the home key of the music. Periods were also commonly used in the classical period, so if it worked for Mozart it will work for us too.
The Contrasting Middle (B)
The contrasting middle is quite overwhelming, because there is no set form to follow like a period or a sentence. By definition, the contrasting middle must be loosely-knit (meaning no define form) and contrast the ideas presented in the exposition. Here’s a process that I’ve been using to write my Contrasting Middles; I will write out a functional chord progression in my tonic key, for example I-IV-ii-V-I. I will then write a simple melody over the chord progression, using the same rules as making a basic idea. There is only one main point here: Whatever motives you used in the Exposition must be contrasted in the contrasting middle. The contrasting middle can be one of the hardest parts because of it’s looseness, so if you have more questions feel free to ask.
The Recapitulation (A’)
The recapitulation weeds out the unnecessary functions from the exposition. This means that the recapitulation must be no more than a restatement of the initial basic idea, followed by a contrasting idea leading into a perfect cadence. If you use a Period for your exposition, your recapitulation will probably look like this:
Standard Period:
[Basic Idea] – [Contrasting Idea] – [Half Cadence or Imperfect Authentic Cadence] – [Basic Idea] – [New Contrasting Idea] – [Perfect Cadence]
Your Recapitulation will get rid of the unnecessary bits:
[Basic Idea] – [Contrasting Idea] – [Perfect Cadence]
Alright Nik, I hope that I cleared some things up for you about small ternary form. It can be overwhelming, and I totally understand your confusion.
Dylan
 

Hey Dylan,
thats really great! Thanks so much for your explanation! 
I really appreciate you using your time to help me out there! Thanks a lot,
May i ask what exactöy you mean by:
There is only one main point here: Whatever motives you used in the Exposition must be contrasted in the contrasting middle.
What exactly does it mean to contrast the Motives?
best
Nik

And is the length fixed like this?:
Expostiion: 8 measures
Contrasting middle:4 measures
Recapitulation: 4 Measures
Or can this length be changed?
thx again
best 
nik

Thanks for the follow up Nik, your dedication as a composer is super cool.
 
Contrasting Motives
A motive is an idea found within a piece of music. Here’s an example from Beethoven’s first sonata.

Notice the idea of the strong quarter notes, and then the triplet sixteenths notes. These are example of motifs. In the contrasting middle Beethoven writes a smooth section, which contrasts the idea of the staccato quarter notes. Take a look.

Notice the differences between the two sections. The slurred notes contrast the staccato notes, the eighth notes in the bass contrast the strong chords previously in the bass. This is what it means to contrast.
 
Measure Lengths
So first of all I hate to say that something musical is 100% set, because the practice of composition is always changing. But…. the exposition is pretty much always going to be 8 measures, because both of the small forms (sentence and period) are 8 measures.
The contrasting middle does not have to be 4 measures. While watching Jon, you will see that typically he does write 4 measure sections, but there is no set structure of 4 measures. The main point of the contrasting middle is to contrast the exposition, and then move into the recapitulation without longing for too long.
The recapitulation is like the exposition, not 100% always 4 measures but very often is. This is because it needs to get rid of the unnecessary material from the exposition so subtract the basic idea repetition (2 measures) and the half-cadence contrasting idea (2 measures) and you are left with 4 measures.
Hope this clears it up for you!
Dylan

Hey Dylan thanks a lot again,that a great explenation there!
So to make sure: the motifs from exposition should be totally differnt. I mean not to be recognized in the motif material from the contrasting middle?
best NIk

Yes that’s correct. The motives must be in complete contrast compared to those in the exposition.

Thanksa lot, that was a great help,
best 
NIk

I am very happy to see a discussion going on here. Great stuff.