A research subject is a broad area of interest, such as the Revolutionary War, legal restrictions on public schools, or the characteristics of Renaissance Art. Once a general subject has been chosen, it must be narrowed down to a more specific topic that can be examined in a research paper. As part of the classroom preparation, your teacher will help you investigate possible topics and, with the help of the librarian, guide your research. The topic should be significant enough to have sources in the library to provide you with material for research. The next step is to write a thesis statement or statement of controlling purpose.