A popular model for breaking up a paragraph concentrates on "chunking" the paragraph into segments, and further breaking up the segments into sentences. Students break the paragraph into five-sentence chunks, beginning with a topic sentence (TS), which is a claim of a thesis; the next sentence proves the topic sentence with a concrete detail (CD), usually beginning with "for example." Two sentences of commentary (CM) -- which are personal thoughts, responses or reactions to the concrete detail -- follow, and a closing sentence (CS) completes the five-sentence chunk. The model is TS/CD/CM/CM/CS.
This model can be broken down even further into individual sentence elements with the use of sentence starters. A sentence starter is a phrase that begins a commentary sentence. The easiest sentence starters, used one after the other, include "this shows that" and "this is because;" however, because it shows a mental step for inspiring the writer to complete the sentence, these are not written down. These, applied to the openings of the third and fourth sentence in each chunk, facilitate writing opinions about the concrete detail even further.
Consider a paragraph about a sibling. Breaking it up yields a humorous topic sentence such as: "My sister is a terrible example for me." It is followed with a factual concrete detail: "For example, she chews gum all the time and puts her elbows on the table." This is followed by sentence starters that begin commentary. For example: "(This shows that) she has little respect for her family. (This is because) she has never been scolded for her actions." Removing the sentence starters yields two ideal commentaries, ready for a concluding sentence.
A process paragraph breaks up into the individual steps of a procedure; a compare/contrast paragraph breaks up into points of likeness and difference; a response paragraph breaks up into arguing points for or against an opinion. These points are the concrete details. A paragraph can have one, two or three concrete details. Since the formula works for eight or eleven sentence paragraphs, you simply add one to two more CD/CM/CM chunks, like this: TS/CD/CM/CM plus CD/CM/CM plus CD/CM/CD/CS.