Expository writing investigates an idea or argument for the purpose of informing or persuading readers. The genre takes many forms, including comparison and contrast, argumentative, analytical and cause and effect essays. You can analyze the effectiveness of an expository work by evaluating its structure, style and use of clear examples and evidence to support its conjectures.
In expository writing, the thesis statement is a sentence that states the essay's main idea. According to the Purdue Online Writing Lab, a good thesis statement is clear, specific and arguable. As you read through an expository piece, see if you can identify a single sentence that sums up its main point and put the main idea into your own words. Grossmont College English instructor Marilyn Ivanovici also suggests considering where the thesis appears. While most authors reveal it near the beginning, others will state the general content and direction, then gradually move toward a more specific statement.
Often, authors have specific plans in mind when they organize their points in an essay. For example, Leslie Marmon Silko's essay "The Border Patrol State" begins with a personal story of a late-night encounter with border patrol agents as she traveled through New Mexico, then transitions into a research based argument that the patrol has grown too powerful. Silko's strategy is to demonstrate her authority on the subject through a personal experience, then reveal the problem's widespread effects. One way to analyze structure is to make an outline as you read, noting each paragraph's focus and how the author transitions from one idea to the next.
Because expository writing is rooted in factual information, authors must provide specific examples and evidence to support their ideas. As you read the body, underline places where the author backs his claims with clear evidence. How the author uses the evidence is also important, as all reasoning must be accurate and free of assumptions or generalizations. You can also consider the quality of the sources. Research studies, scholarly journals and government sources are considered more credible because experts verify and review the information. By contrast, personal websites, partisan organizations and popular news sources can easily be biased or flawed.
Expository writing features a variety of different writing styles, from the straightforwardness of academic articles to the satire and humor of personal essays. You can examine the author's word choice, attitude and sentence structure to determine how you would describe the piece's style. For example, Terry Tempest Williams' essay "The Clan of the One-Breasted Women" shares her personal experience of watching from her family suffer from breast cancer induced from nuclear testing near their Nevada hometown in the 1950s. The essay's righteous anger, self-disclosure and clear evidence of the government's disregard for civilians during the tests creates a style that is both personal and informative.