What is Expository Writing?

Dear Dr. D,
I've been researching expository writing and keep getting this type of definition: Expository writing is devoid of descriptive detail and opinion. It contains just the facts.
How can I reconcile that statement with the Schaffer method? 
Thanks, Annette

Dear Annette,

Aristotle deserves much of the credit for initially classifying the modes of discourse into deliberative, forensic, and epideictic. Over the years, however, teachers and professors have delimited the modes to help teach writing. Typically, they are divided into four categories: argumentation, narrative, literary analysis, and expository. We all know that the modes are not as mutually exclusive as some would think; certainly, an argument may have description, analysis, and even narration. However, let's get to your question. "Expository" is too broad of a term to give such a narrow definition as the above one.
There are many different forms of exposition: process analysis, exemplification, definition, classification and division, comparison and contrast, cause and effect, and problem and solution, to name the most popular. Look at that topic sentence handout that I gave you. You’ll see some of the various forms, topic sentence examples, and prompt suggestions.
The definition you provide lends itself to the type of expository writing that does not require commentary or analysis (e.g., explaining a process, explaining a plot, providing an accounting of what was taught in class today, inductive reasoning by giving examples only). It sounds like one that would be given by a teacher in the sciences and social sciences who might first ask her/his students to describe something, perhaps a behavior or phenomenon. Her/his next step might be to take the evidence and look at causes and effects. The final step might be to create an argument about it. So, the definition you are giving me suggests that it might be part of a progression –the first part, or providing the facts. In other words, first, writers collect the evidence (expository), then they might evaluate it (argumentation).  
Expository comes from the word “expose.” The prefix “Ex-” comes from Greek through Latin and means “out, or away from.” The root of the word comes from the Latin verb ponere which means “to place.” Translated literally, exposition means “to place out,” and what we are placing out is the information. So, I can see why some would argue that it is fact only. However, the definition you provide is not the norm for state and national standards that ask students to analyze the information they present – also considered expository/explanatory.
Keep reading and writing!
Happy New Year,
Dr. D'