I did not realize that English was so scientific until we covered the areas of Definition, Classification and Division, and Process. We will start by looking at definition. When you look to use definition in your writing it is important to consider who your audience is. If you are using domain specific terms, you would not have to define those terms if your audience is in that domain, but if your audience is outside that domain you would have to define the terms in further detail. Your writing will have more or less definition depending on how much classification and division is put into it.
Classification and division is the process of segmenting your rhetoric into different parts and then breaking down each segment. It is easiest to identify classification and division in expository text, but there is classification and division in any writing since the author is going to use some type of process to break it down. For example: In cause and effect writing you can break the text down and list all the causes and all the effects in the writing. In compare and contrast you can classify the writing in what is being compared, and then divide it by listing the differences that were pointed out.
The easiest of these concepts for me to understand it process. Since I am a computer tech I use process all day long. When someone calls me on the phone with a technical problem I first use the process of asking sets of specific questions to identify the problem, and then use the process of giving a specific set of instructions to solve the problem. In my field the processes that I use are always changing because technology is always changing. In the case of writing, process is used often. Some examples of process are: food recipes, any instruction manuals, troubleshooting guides, and repair manuals.
Definition, Classification and Division, and Process work together to complement each other. For example, to write a repair manual you have to classify the different areas of a car and then use process and definition to break down those sections even further. When considering who your audience is these three things have to be taken into account. If you were writing a repair manual for experienced car mechanics it would have much less definition then if you wrote one for the layman mechanic.