If your professor is allowing you to pick your own topic, you'll want to choose carefully. Follow these steps to create a topic that can be researched:
If you're still uncertain, try checking out the Opposing Viewpoints database. This database collects information on controversial topics and is a great place to look for ideas that will have a lot of supporting material. You might also want to check the news for items of interest that you'd like to research further.
Once you've selected a topic, it's time to move on to Step 2: Develop a Search Strategy.