Start with your textbook or course readings to look for the main ideas or names associated with the topic. As you read, write the questions or comments you have --- they are excellent topics for the research paper or the presentation. Write any suggested titles or articles that are mentioned in the textbook or a course reading.
Browse Wikipedia. Studies indicate that articles on science topics are generally highly accurate and are carefully edited in Wikipedia. The list of recommended sources at the end of each article can also be very helpful.
Check out the Math News tab in this guide for a variety of interesting topics in mathematics.