To narrow a topic that is too broad for a particular assignment, ask yourself the following 5 W questions.

Broad topic: eating disorders

• Who? What population am I interested in? (Consider age, gender, race, or ethnicity.)
• What? What types of eating disorders am I interested in? (Anorexia, bulimia, binge-eating?)
• When? What timeframe am I interested in? (Consider current, historical, particular stage of life.)
• Where? What location am I interested in? (Consider countries, states, cities, and regions.)
• Why? What do I need to evaluate? (Consider causes, treatments, outcomes.)

Once you've answered these questions, combine different combinations of the areas you're interested in to create an interesting, manageable research topic. 

Narrower topics:

• causes and treatment of anorexia in teenage males in the United States
• changes in treatment of bulimia from the 1950's to the present
• prevalence of binge-eating among children of divorce

Sometimes your selected topic will be so narrow you won't be able to find enough sources when you research it. If that's the case, you can broaden your topic using the same 5 W questions listed above. 

Really narrow topic: causes and treatment of anorexia in African American teenage males in St. Louis in the 1980s

• Who? Can I broaden my topic to include a larger population of people?
• What? Can I examine a larger problem or multiple related issues?
• When? Can I broaden my topic chronologically?
• Where? Can I broaden my topic to include a larger geographic region?
• Why? Can I evaluate a broader aspect of my topic?

Broader topic: causes and treatment of anorexia in teenage males in the United States

Yes, you can use Wikipedia to find background information on your topic, but information available via the SLU Libraries is much more reliable and authoritative! Search these collections of reference eBooks to find quality background information on your topic.