I'm getting ready for the second week of conferences. Many of the students who participated last week had questions regarding the focus of their expository essay. The main thing that I urged was to make the topic as specific as possible. General themes like fear, hope, or leadership need to be narrowed down to something manageable for a short 750 word essay. The other thing that I stressed is to stay away from trying to persuade. The point of the paper is to help explain. Here's a page that may be useful as you work on your essay.