You really should be coming up with your own ideas ... that's part of the reason why they have given you such a broad topic. As I posted on here a few days ago, I'm sitting on a presentation panel for potential GTP-ers next week - imagine how I will react if I see someone delivering an idea which was suggested on here. I'm just giving my thoughts on the presentations, I'm not going to be making the final decision, but there are plenty of people who post in these forums who ARE the decision makers ... I would also bet that there are even more people in those positions who READ these forums, even if they don't post. One piece of advice however: leave them wanting more (by them I mean both the pupils and the people who are judging your presentation/interview/lesson)!