This pattern allows you to either divide a topic into it's component parts, or to categorize (or classify) a group of related items or events. When dividing you begin with one central topic and break that down into multiple parts. Think about medicine. Medicine is one of several branches of science and it can be divided into numerous categories or specialties. Doctors can specialize in internal medicine, dermatology, the immune system, feet, ears, eyes ect.
Classification works in the other direction, putting things together based on shared qualities or characteristics. Imagine that all those doctors are at a doctor convention and in order to make sense of them you need to organize them into groups according to their specialty. Either way you end up with doctors grouped by specialty but division illustrates differences, while classification focuses on similarities.
The Principle of Classification is whatever rule or characteristic ect. you are using to determine which items are grouped together. For example, if you were classifying clothing you might classify by color and put all green clothes into a category, with all red clothes in a separate category, and all blue clothes in a third. Your principle of classification would then be color. Or you might classify by size, putting smalls together, mediums together and so on.
Remember to ONLY USE ONE PRINCIPLE OF CLASSIFICATION AT A TIME otherwise your designations will be confusing and irrelevant.
These buttons are classified (sorted or grouped) by color. Looking at this picture, what other characteristics might you use for grouping them?
Topic Sentence
As in any other paragraph, you'll want to begin your classification/division paragraph with a topic sentence. In this pattern, that topic sentence should introduce the reader to the items or concepts that you'll be categorizing and explain what the principle of classification will be.
Supporting Sentences
Your supporting sentences should identify the different categories into which you're classifying or dividing the main topic (i.e. clothes, doctors, ect.), with an explanation as to what makes that category different from the other categories. For example, why do we divide dentists and brain surgeons into different categories?
Concluding Sentence
Bring your paragarph full circle with a concluding sentence that describes why all of these categories are related, and why the distinctions you've pointed out are important.
Sequence
Writing a classification/division paragraph produces something like a list, but it's important to keep a logical order to your categories. Figure out what your order will be before you start and then be consistent to help your reader understand.
can be divided is a kind/type/part of
can be classified falls under
can be categorized is related to/associated with