I would suggest to possibly think about three different locations within your school where you could potentially do the presentations. If the presentation is simply informative than this should be fairly easy. If they are performance based than it would allow the students to learn how anyplace can become a stage. Be creative and ask the Athletics department to use one of their spaces. Use the Library. Use the conference room in the main office. The face that a new location is thrown on top of everything it may help with keeping the day fresh and different form the previous one. Not sure if this helps at all or can serve your needs. This was just what came to mind.
Wish all the best!