Musical DNA – Small Ternary Form

Small Ternary Form and Small Binary Form

Musical themes don’t just stop at sentences and periods. If that was the case, we would be severely limited on the scope of music we could write. There are two other theme types I want to talk about before we move onto bigger and better things. They are the small ternary form and small binary form. We’ll be talking about the small ternary form today and then the small binary form in a few more days. I am splitting them up so they don’t get too long.

Musical Phrases Unleashed Recap

We have covered so far:

  1. Musical Sentences
  2. Musical Periods

If you haven’t read these posts yet, please go back and read them now. I reference quite a bit from them, for this article.


So let’s talk about the small ternary form and small binary form. These forms, along with the sentence and period, are really the basis for most classical music. In fact, most music from the rennaissance through the romantic can be seen through the lense of these forms.

But let me be clear, I am not saying that most music fits these forms exactly. Music has a way of not fitting into the cookie-cutter examples. Instead we need to look at them as prototypes, or even better, archetypes. They are kind of like DNA. DNA can have millions of different combinations, and create infinite variety. But DNA only really contains four molecules, just rearranged over and over again.

Small Ternary

We start our conversation off with small ternary form. The small ternary form is, as you would guess from the name, basically a three part theme. It is commonly written as A-B-A’. It has three formal functions.

  1. Exposition (A)
  2. Contrasting Middle (B)
  3. Recapitulation (A’)

This mirrors another, another large form, the Sonata Form. But the Sonata Form is a little too big to cover today, so I’ll save it for another post.

Let’s listen to a complete small ternary form.


The Exposition

The exposition in small ternary form is normally made up of a sentence or period, as discussed in the previous posts. Normally in an exposition, these two theme types appear in their basic form, or a hybrid form (mixing elements from sentences and periods). When they are 8 bars, and contain all of their basic formal functions, they are known as tight-knit themes.

The Contrasting Middle

The contrasting middle section in small ternary form gets its contrast mostly by harmonic means. The goal for the contrasting middle section is almost always dominant harmony (V). The contrasting middle has a few different charcteristics from the expositions as well:

  1. Tends to be much looser in organization
  2. Creates instability (mostly harmonic instability)
  3. Frequently changes texture

Tight-Knit vs. Loose Organization

Let me talk a moment about tight-knit themes and loose themes. These are terms, once again from Classical Form, by William Caplin. I think they are excellent ways of thinking about how to use these forms for real composing.

Tight-Knit Form

Tight-knit usually refers to the basic theme types, the sentence and period. They are both 8 bars, and can be explained relatively easily. They also have a number of hybrids, mixing the parts of both periods and sentences together.


  1. Compound Basic Idea (an antecedent without a cadence) + Continuation
  2. Antecedent + Continuation
  3. Antecedent + Expanded Cadential (cadential takes up the entire continuation)
  4. Compound Basic Idea + Consequent

Loose Form

In comparison with tight-knit themes, loose themes use certain devices to add material and expand the 8 bar themes beyond their usual scope:

  1. Extension – Adding on extra material. This is usually accomplished through further fragmentation of ideas. It is also very common in cadences.
  2. Expansion – “Internally lengthening components” of a formal function from there typcial length in a tight-knit theme.
  3. Interpolation – Adding on extra material, that has no other formal function.


The recapitulation is the final part of the small ternary form. This is commonly a tight-knit theme. It is called the recapitulation because it brings back the material from the exposition. Very frequently it gets rid of unnecessary material as well. What is unnecessary? Let’s look at a period for example.

The period has an antecedent phrase, consisting of a basic idea, and a contrasting Idea with a weak cadence.

It also has a consequent phrase, consisting of a repeat of the basic idea, and a new contrasting idea with a strong cadence.

Just looking at the words above, you can clearly see what is “unnecessary.” It is material that is functionally redundant.

  1. Basic idea
  2. Contrasting Idea with a weak cadence,
  3. Repeat of basic idea
  4. New contrasting idea with a strong cadence.
A period, with the functionally redundant material taken out, is essentially a consequent phrase.
This allows you to take a simple 8 bar theme, and turn it into a 4 bar theme. But it doesn’t just stop there.

You can just as easily expand it with the devices mentioned earlier, as well as a codetta, which is kind of like multiple cadences after each other, helping to dissipate the built up tension during the phrase. I’ll be talking about the codetta, and other framing functions, as well as interthematic functions in a few weeks, when we look at the first movement of the Symphony (no, I haven’t forgotten what this is all about).

Stay tuned to find out about the small binary form, and how it differs from the small ternary form.

I am working hard on sketching out the movements of the Symphony. I want to make sure that I post stuff that is good, so I am taking my time on it. It will be coming soon.

As usual I’d love to know what you think.

Until next time,


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  1. says

    I have been studying music theory off and on for four years now and have never seen such clarity and exposition as your presentations. What was once difficult for me to understand has become far more comprehensible thanks to your style and efforts. You have gained a sincere follower and supporter of the generous time that you spend making this knowledge available in such a clear way; and for free no less. I will definitely add your link to my website as one of my favorites. Please keep up the great work. Yay you!

    Tarynn M. Witten, PhD, LCSW, FGSA (and beginning composer)

    • Jon says

      Thank you Tarynn for the kind words. I wish I could say that I came up with this stuff, but I am just standing on the shoulders of giants. Unfortunately most people don’t get a chance to read any of the really great music theory books out there, because there are a lot, and they are eye opening. The book that really changed my perspective on form is Classical Form by William Caplin. My goal is always to write something that answers the questions in a way that I wish they could have been answered for me when I was just starting to learn. I also want to open people up to the possibilites that music theory can bring for their compositions. Too many people think theory stunts creativity, but it is far from the truth. I’d love to hear some of your compositions. If you have any online, post a link.

  2. john says

    WOW! I love the way you explain these concepts in the most clear, concise, understandable way possible. This website truly democratizes music, taking it out of the ivory tower for all to enjoy. I love the way you avoid using the arrogant prose which so many “intellectuals” and “educators” are apt to use. They seem to delight in deliberately making incomprehensible subjects even harder to understand, while you achieve the exact opposite. This is a site for the everyman. The common person. I respect that a lot.

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