There is no ethernet in classroom, wifi and cellular networks are being jammed, to prevent misuse of various gadgets by students.
I highly doubt cellular is jammed, as that is very much illegal and can land you in jail.
I spent many years (professionally) tracking down radio frequency jammers in the field across the United States. If you're jamming in licensed cellular spectrum, the odds are very good that the cellular network operator will detect high uplink RSSI levels and will (eventually) send someone out to investigate.
If they find you*, they will probably first try to talk to you and/or send you a polite, but firmly-worded letter letting you know that you're interfering with them. Either of these are (in my experience) usually sufficient to get the "offender" to stop using their jammer, and thus the FCC rarely gets involved in these cases.
On the other hand, if you are jamming GPS, certain aeronautical navigational aids, automobile remotes, or emergency frequencies (police, fire, marine channel 16, etc.), then it is much more likely that someone working for Uncle Sam will come looking for you. I could (but probably shouldn't) tell you some very interesting stories.
And if you're jamming unlicensed spectrum (like WiFi, ISM, etc.) it's extremely
unlikely that anything is going to happen to you.
Again, just my experience spending many years doing this on almost a weekly basis.
*Edit: in order to be effective, a jammer must produce a signal that is wide, loud, and always on. This also makes them VERY easy to locate.