Another option is to download, install and configure your own IRC server (IRC daemon) to your instructor machines. If more than one, you can even link them all together to make your own IRC network throughout the campus.
If installing to a Linux machine, you can look at Ratbox (simple and light weight) or Charybdis (a descendant of ratbox) or ircd-seven (a descendant of charybdis).https://www.ratbox.org/https://github.com/charybdis-ircd/charybdishttps://github.com/freenode/ircd-seven
If the instructor machines are Windows, you're pretty much stuck with one of two crappy options. UnrealIRCd and InspIRCd.https://www.unrealircd.org/https://www.inspircd.org/