Who are you writing for? You want to ask yourself that question every time you begin a writing project. And you want to keep your audience in mind as you go through the writing process because it will help you make decisions while you write. Such decisions should include what voice you use, what words you choose, and the kind of syntax you use. Thinking of who your audience is and what their expectations are will also help you decide what kind of introduction and conclusion to write.
Your instructor, of course, is your audience, but you must be careful not to assume that he or she knows more than you on the subject of your paper. While your instructor may be well-informed on the topic, your purpose is to demonstrate your knowledge and fully explain what you’re writing about, so the reader can see that you have a good grasp on the topic yourself. Think of your instructor as intelligent but not fully informed about your topic. Think of your instructor as representing people from a particular field (historians, chemists, psychologists).
Another approach is to think of your audience as the people who make up the class for which you are writing the assignment. This is a diverse group, so it can be tough to imagine the needs of so many people. However, if you try to think about your writing the way others from a diverse group might think about your writing, it can help make your writing stronger.