The structure of your essay's introductory paragraph is critical. You need to employ an engaging opening line that grabs a reader's attention and piques his or her interest in what you are going to say throughout the rest of the essay. You also need to begin explaining a context and reason for what you are writing, all while building up to one sentence that lets your reader know exactly what your essay will be about in detail.
The most important sentence of your introductory paragraph (and your essay as a whole) is your thesis statement. As the Purdue Online Writing Lab explains, your thesis statement needs to be a clear, specific assertion of your essay's focus, and typically it will be the last sentence of your introductory paragraph. A good thesis statement will direct your reader's attention toward a narrow and defined subject, and the rest of the paragraphs in your essay will refer your reader back to it.
The role of each body paragraph is to explicate one main idea about your essay's thesis statement. A successful body paragraph will be structured with tight focus and precision. Every sentence in a well-constructed body paragraph is tied directly to the aim indicated by the paragraph's topic sentence.
A paragraph's topic sentence is like a mini-thesis statement that announces the main idea about the paragraph in which it is featured. Everything that follows it will serve only to illuminate that one idea. When self-editing, beginning writers should identify and underline every body paragraph's topic sentence, then read every sentence that follows it in the paragraph. If you read a sentence that does not fit with the underlined topic sentence, you know that you need to move that sentence to a different paragraph in order to maintain good paragraph structure and overall message unity.
As Pat Bellanca at the Harvard University Writing Center explains, your concluding paragraph is very important to your essay's overall effectiveness because it is in this paragraph that you get to shape the final impression you leave with your reader. In this paragraph, you will want to try and encapsulate all of the main points of your essay. It is very important that you never introduce new information in a conclusion. A satisfying conclusion features a final sentence that springs from the supporting details of your body paragraphs and recasts your thesis statement in a way that ties your essay together for your reader.