If this is the schools version of the intercom system, might not be such a fot idea to jam it up. With all the terrorism crap going on in the world, USA and Great (ha ha) Britain be major targets these days. Certainly don't want to miss any important annoucements. Maybe that new student, the arabic kid, brings an unusally large book-bag to class one day, and the teacher is a little concerned... Or maybe they decided to give everybody the rest of the day off, and want to empty the school one class at a time, kind of bummer being left behind...
Sure these kinds of toys can be fun, but in school everybody will want one. The circuit for a TV Remote Jammer is very simple and cheap, and lot easier to do than jamming Cell phones. The school's intercom system is for important stuff.
When this thread started, it was about the PA system. And, yeah I could see how cool it would be to make a few inappropriate annoucements (my get a few days off from school for it, never understood how that was punishment for the student). Can each teach talk over the PA from any classroom? Or are all annoucements made pretty much by on person?