Your thesis statement will set the tone, organization and define the purpose of your entire expository essay. According to the guide on expository writing at Grossmont College, "A thesis concisely states the center point of the essay." Your thesis will come down to a single thesis statement, a short sentence that states exactly what your essay is trying to explain. The thesis statement usually, but not always, appears in the introductory paragraph to an expository essay.
In exposition, thesis statements are supported by examples, facts and details. Each paragraph in an expository essay forms its own argument and makes specific points that support the overall idea of the essay. While each paragraph contains specific, unique ideas, their content must tie back to the original thesis statement. This is why organization is an important part of essay writing. At no point in the essay should the reader forget what the essay is trying to explain or prove.
Grammar, clarity and tone are also important elements of an expository essay. While the tone of the essay should be authoritative, it should also be engaging. Grossmont's writing guide suggests that your tone should convey your attitude towards the subject. You could be enthusiastic, serious, comedic or angry--as long as you are able to keep the reader's attention. Grammatical errors will make your essay difficult to read and will also make it harder for the reader to take your opinion seriously. If you want to know whether your essay is easy to understand and read, have a friend read it over before you write the final draft.
It's important to learn exposition even if you never plan to become a teacher, academic or writer. There are many situations in the work place when you will have to apply the skills that you have learned when using expository writing. This includes writing business reports, memorandums, oral presentations speeches and even emails. Whenever you sit down to read a magazine, newspaper or non-fiction book, you will understand the methods the writer used.