Very easy. The absolute best thing you can lecture on is what you like most. What you know most about. Your hobby? Cars, computers, sports, etc. You have to be in love with the subject to be great at lecturing about it. Sure, anyone can lecture about any subject they research, but if you have the opportunity to lecture about something you really have a passion for.. well, 4 minutes will be so short, you’ll have to practice to keep it brief. It’s like you just got a new best friend, and they ask you about something you know a lot about – you want to tell them all about it. Good luck & have fun !

I think the lecture within 3-4 minutes is a race against time, that is, you need to prepare your topic and the content well. You have to ask your self what topic is most interesting to you, then find supporting details from good references or from the wikipedia website. Thus it should be contemporary such as the issues of ‘global warming’, or ‘clean & green environment’, or ‘academic culture’, etc.

Be precise, according to my experience, this is my timeframe:

< 1 minute: introduction 2-2:30 minutes: the issue, supporting details, example and impact. < 1 minute: conclusion. Good luck.

The key phrase in your question is “on any subject I like” The subject has to come from inside you and be something you’re passionate about. What are you passionate about? If you are interested in it, your audience will find it interesting. The very first speech a newcomer gives in Toastmasters is called an “Icebreaker” and is telling the audience something about themselves. Choose a subject near to your heart and about which you are passionate. Good luck!

What about the capybera? It’s like a huge guinea pig that lives in the rain forest. You could find some pictures. I think they’re cool.

What about Atlantis. Pretty interesting and sometimes controversal because of the whole mystery about it. Could start up a debate!

It’s possible to determine a community’s drug use–type and amount–by checking a small amount of sewer water. Drugs and human elimination are always draw the interest of teenagers.