Your choice of topic will be guided by your assignment, whether it's a biology class assignment or a composition paper. Read the assignment carefully and consider these questions:
1. What type of thesis question does the assignment require? Is it an exploratory paper, in which you discuss both sides of an argument? Is it a persuasive paper, thus calling for an opinion statement at the start? Or is it a typical "research paper," in which you discuss both why the question is important and come to a conclusion.
2. How much "space" (or how many pages) do you have to explore the topic? For example, for the question of "how does religion affect American culture?" is too broad for a 3 to 5 page paper (and would probably be too broad for a single book).
3. What type of evidence do you need for support? Original research (research you perform on your own, such as a lab or a qualitative study)? Popular sources? Scholarly articles?
4. What do you already know about this topic from class and what parts of it caught your interest? The best research papers emerge from your interest in a research area--if you're not interested in it, why should the reader be?
Make sure to do some reading on your topic before you start, especially if you're new to the field. You can check an encyclopedia for background information (even Wikipedia is good if you're stuck), and check the news to see what the conversation is.
If you find that your topic is too broad for the confines of your assignment, or your teacher tells you that your topic needs to be more narrow or specific, consider these questions:
1. What? Are there different aspects or sides to the topic? Are there multiple viewpoints? Why is it an important question?
2. Who? Which groups are affected by the topic area in question? Who is involved in the discussion? Is culture an aspect?
3. When? Is this topic a contemporary concern, a question that affects people today? Is it a topic that can be explored across time period? Is it a historical concern?
4. Where? Is the topic confined to a specific geographic location? Does it affect one area more than another, or is it universal?
Sometimes exploring one or two of these questions, rather than all of them, is more appropriate for the scope of your assignment.
If you find that you can't find enough evidence for your topic, you might want to broaden it. However, make sure that your lack of evidence is not caused by search issues. Sometimes it's difficult to find the appropriate sources for your topic. Check the Keywords and Sources tabs before you broaden your topic.
If your topic is indeed too narrow, you can try different approaches to broaden it. One technique is to explore another aspect of the topic. For example, if you're looking at incidents of racial discrimination in one town, you might broaden the scope to encompass similar cities or even cover an entire state. You can also can find synonyms for the keywords you are already using, such as "United States of America" instead of just "America," or "The Great War" instead of just "World War I." You might also try adding different types of sources. For example, if you're researching women's roles in the home during the 1920's, you can use newspaper articles and advertisements, in addition to looking at advice literature.