Stay relaxed, have fun, the judges are people too.
While it’s importance to practice and rehearse, don’t make it sounded “scripted.” Keep it lively, entertaining, and conversational. The judges are going to hear a bunch of presentations, so make sure you don’t bore them.
How can you make your presentation stand out? The judges are going to see powerpoint after powerpoint, and hear the same stuff from everyone. That’s not to say you don’t use a powerpoint, but make sure it’s unique, memorable, and informative (as well as easy to read), and don’t make it the only source of substance. Use the powerpoint to reinforce the rest of your presentation rather than the focal point.
Of course there are a number of alternative and additions to ppt. You can use posters, videos, scrapbooks, physical examples/evidence, or just about anything else. Use what you can do and use the best.
The judges will vary from event to event, and even individual to individual. Some will be sticklers about time (especially in events with lots of teams registered for CA), but others will allow you run over a little bit. Some will be more formal, while others will just let it go with the flow. Some will ask questions during your five minutes (although rare), others won’t.
The questions, too, will have some variety. Typically they will ask you about elements that you either didn’t cover in your essay/presentation, but they may also ask questions about items they don’t fully understand, team organization, your school system, or more abstract topics. Some questions I can recall from my three presentations to Chairman’s judges.
“What do envision your school’s role in FIRST to be in the future, and how do you want it to change?”
“Can you expand upon the relationship the mentors/sponsors have with your team?”
“How did you personally become involved with FIRST?”
Good luck, and stay loose!