correct - or any other DNS filtering system (and systems that do not do HTTPS filtering and/or let Google QUIC out).
My kids know how to do it (at school, they cannot at home). I just warn them of the consequences and tell them to let all the friends know, so if they are caught they are just part of the 'crowd'. If one person is doing it, then they're breaking the rules and can be punished. If everyone is doing it then there is fundamental problem with the system :)
Wouldn't it be easier to simply tell them they're not to do it at school - why encourage them to break the rules?