Please start thinking of a topic - brainstorm, mind map, randomly select... actually, talking about something you are passionate about is often a good idea. Alternatively, try being amusing. The audience must be entertained, to keep their interest, even if you are dealing with a serious topic. Avoid making lists of facts to repeat ad nauseum.
The speech must be 3 minutes long exactly.
We will develop the speech in class. You just need to start thinking and researching ideas.
Good luck - try to make it fun!