Remind students that most expository essays consist of three basic parts: an introduction with a thesis statement, a body with limiting ideas that support the thesis and a conclusion. Therefore, they should look for the topic of the essay toward the beginning of the essay.
Instruct students to get out a pencil (not a pen) so that they can underline key words, make notes in the margins and, if need be, erase their jottings.
Encourage students to look for a statement that contains a sharp focus. The topic sentence should be clear and understandable but also one that requires further explanation from the writer. These explanations will be fleshed out in the subtopics.
Search for a strong declarative statement from the writer, such as: "I never knew my fiancé was such a slob until we moved in together," "Working at that clothing store was the worst job I've ever had" or "She is quite possibly the most inept cook I've ever seen in action." Most likely, such a declarative statement is the topic of the essay, so underline it (or put a large "T" next to it, for "topic"). Locating the supporting subtopics will confirm your guess.
Search for statements that support, embellish and elaborate on the topic of the essay. These statements are clear and direct, but they do inspire curiosity, which they should. If the essay is well organized, each subtopic should be contained within its own paragraph (although some lengthy subtopics may go on for several paragraphs).
Underline these statements and then compare them to the topic sentence. Using these examples, credible subtopics might include: "After working in the garden, my fiancé refused to take off his work boots and tracked mud into the house every day," "Most days, I opened the store at 7:30 a.m., didn't even have time to eat a sandwich and then closed the store at 10 p.m." and "She once started a small fire because she insisted on removing a hot dish from the oven with a paper towel instead of an oven mitt."
Review the presumed subtopics. While they should enhance the topic sentence, they also should be worthy of amplification on their own -- hence creating the body of the expository essay.
Eliminate statements that do not amplify the topic, even if they are interesting. For example, a fleeting reference to the fiance's eye color or the inept cook's favorite bathrobe has nothing to do with the topic -- and therefore doesn't qualify as a subtopic.
Review the expository essay -- and your underlined topic and subtopics. Together, they should display cohesion, unity and a progression of ideas -- and help students appreciate a well-crafted piece of writing.