Can we look at this from a strictly technical standpoint?
Student Jane takes her fancy laptop home and connects it to her home LAN via either WiFi or some other method.
What happens next?
Before Perv Principal John can "turn on" Jane's webcam, he would need to log into her laptop, yes? And to do this would need an IP from an ISP that more than likely issues dynamic IPs. How is John doing this? Unless...
If not the above, Jane's laptop, once connected to the internet, has special software that opens some sort of connection with the school/Principal John? If this is the correct scenerio, wouldn't such software be easy to detect? Could Principal John claim that the software was not installed by them but was instead malware of some sort? Did this software connect with the school via a VPN? Most likely not, so the contect was exchanged via unsecure means, making the subject being viewed vulnerable to public viewing/hacking.
This just goes on and on on so many bad levels.
Most likely a call home application. Could be encrypted as well, likely not.