Help with VNC (via school Wi-Fi) without consent? Opsec I'm in a tough situation and am hoping you can help me out.

As a student in California, USA, our teachers sometimes require us to sign on to the school's wireless network.

Supposedly, they have an application where they can not only listen to each device's incoming/outgoing traffic but also view our screens in realtime (sort of like a VNC client).

For obvious reasons, this drives me insane. Other than using Chrome extensions such as HTTPS Everywhere and turning on FileVault (Full disk encryption), what else can I do? I know the VNC client likely runs off of  some malware installed on my computer (without my permission, of course). Where might this sofware be hiding and/or be found?

I'm running High Sierra 10.13.2.

PS: Would running a system such as Tails be a good idea? (tails.boum.org).

Thanks again!
The only way they are going to be able to watch your screen is if you have installed something specific to allow them to do so or they have a password and you have screen sharing (and or remote management) turned on.

So turn off screen sharing (System Preferences > Sharing. Uncheck screen sharing and remote management) and change your password and any other passwords on the system in System Preferences > Users &amp; Groups.

This all presupposes this is YOUR Mac and not one provided by the school. If it is provided by the school they likely have it locked down so you can't make those changes because the computer does not belong to you.