Here are some tips to help you with your topics.
Avoid speech topics that deal with fixed beliefs like abortion, capital punishment, religion and so forth. People have spent many years deciding what they think about these topics and you are not likely to change their minds in a four to six minute speech. Don't set yourself up to fail.
Sources to consider for Topic Ideas:
Public Opinion Polls
The Taking Sides Series presents current controversial issues in a debate-style format designed to stimulate student interest and develop critical thinking skills. Each issue is thoughtfully framed with an issue summary, an issue introduction, and a postscript. An instructor's manual with testing material is available for each volume.
Listed below are a few examples, but to see the rest of the collection available through the Library click here.