It's important to start your research journey by looking at some secondary sources. This will help you understand how to place your topic in the larger historical context. History books and other reference materials help you understand why your topic is important and how it relates to economic, social and political developments of the period. A good National History Day project draws on several kinds of secondary sources, in addition to your own original interpretation of primary sources. Look at monographs as well as general reference books to get background on your topic. You will discover that professional historians bring their own biases to the topics they research, and you should seek more than one perspective on the issues you are researching.
Look for general information in encyclopedias, special historical dictionaries, and historical atlases. General encyclopedias such as World Book can provide you with basic information, while subject encyclopedias such as the Encyclopedia of the North American Colonies or the Encyclopedia of American Economic History provide a bit more detailed information. Encyclopedia articles often have bibliographies which can direct you to some of the major secondary sources for a topic.
Popular Periodical Literature
Popular magazines, indexed in the Readers= Guide to Periodical Literature, can give you ideas for and some general information about particular topics. National Geographic provides general information on provocative topics. Many other magazines and newspapers publish articles dealing with individuals or historical issues. For example, in the mid-1990s many U.S. newspapers and magazines wrote about Nelson Mandela, whose political activism helped revolutionize South African society by ending apartheid, and who became president of South Africa in 1994 after spending 28 years in prison for his politics. Starting a project on apartheid, you might begin here, and get ideas for interesting topics about the events that led to this revolution.
Yes, really! Your textbook can be a great place to get ideas for topics and find out about the general context of your topic. If you're interested in the invention of the telescope as it revolutionized astronomy, first do some background reading on the scientific revolution as a whole, perhaps in a general textbook on European history. This will help you understand how your topic fits in with the Abig picture.
General Historical Works and Monographs
Move from the general to the specific. A book on the history of astronomy will provide more detail than a general text on European history. Try a keyword search at a larger library and you'll find dozens, if not hundreds, of books on the history of astronomy and related sciences. Another way to find secondary sources on your topic is to check the notes and bibliographies of books you've already found. And sometimes you might be able to find an entire book which is a bibliography on your topic; these books will be in the reference section, especially at university libraries. A good guide to the best books in just about any area of history is The American Historical Association's Guide to Historical Literature, 3rd ed. (New York: Oxford University Press, 1995).
Historians don't always write books. Smaller essays on specific topics can be found in scholarly journals. These are periodicals similar to magazines, only they are specifically focused on history topics. There are general journals, like The Journal of American History, and more specific ones, like The History of Education. Academic journals can usually be found at college and university libraries, and there are often indexes to help you find an article on a specific topic. Or just peruse some of these journals to see what kinds of questions professional historians are asking about your topic.