Always write a single paragraph of at least six sentences and at most 200 words in support, elaboration or defense of a single well-defined claim expressed in the key sentence.
You have decided when you will write and what you will say. This rule now tells you what you should do. Or, better, what you should make. The paragraph is the unit of scholarly prose composition; you are not writing scholarly prose if you are not writing paragraphs.* The paragraph will express a justified, true belief you hold and then, depending on the needs of your reader, provide support for it, elaboration of it or a defense of it against the reader’s objections. The problem of writing a paragraph can really only be solved with a reader in mind. That’s important to remember.
The rule here may seem a bit rigid but notice that it defines a minimum and a maximum. You can write eight sentences and 187 words and still be following this rule. Ezra Pound had a good way of thinking about form: think of it as a center “around which”, not a box “within which”. The key sentence provides you with a focus, the six sentences mark out a minimum level of complexity, and the 200 words sets an outer boundary. This tells you what you are heading for, but gives you a lot of leeway about where exactly you end up. If you experience it as a constraint, you are approaching the problem with the wrong attitude. Having 27 minutes to write at least six sentences and at most 200 words should feel liberating, not oppressive.
I am suggesting you make writing paragraphs the rule rather than the exception. Don’t think that paragraphs are easy or boring to write. Don’t think they have to be boring to read either. Asking you to write at least six sentences and at most 200 words about a single thing doesn’t tell you very specifically what you should be doing. It merely rules out a lot of things you shouldn’t be doing. There is a great range of freedom for creativity within that form, arguably greater than if I asked you to write a sonnet.
“Aim small, miss small,” sharpshooters say. What they mean is that if you aim for the man and miss, you miss the man. But if you aim for a button on his shirt and miss, you may still hit the man. That is the virtue of having a focus. And a limit. It lets you find your composure. It lets you compose your paragraph.
*I don’t have to imagine readers that would object to this generalization. I have respect for these conscientious objectors; I know where they’re coming from. (I’ve been there.) I want to meet them halfway by granting that not everything in a piece of academic writing needs to be strictly “scholarly”. These rules, I should repeat, are here for those who are making a deliberate effort to improve their scholarly prose style. These people should be writing paragraphs.