For a long time now I feel the need to teach Linux in my ICT classes as this opens a whole new world of possibilities and insights. Seeing only windows is a very limited view, especially never working on the command line (both windows and Linux) is ok for a user — but not for a technician which are taught in our laptop classrooms. A huge amount of servers (especially in a technical or computing environment) use linux, Plansee, the company which founded our school, uses Linux to manage their whole worldwide server infrastructure.
The option to use a Linux box is very rare (in our schools) so an easy workaround in our laptop classrooms is to use a virtual box. A reasonably small Linux distro, e.g. Porteus, can be installed in minutes. First steps using such a box using the command line including communicating via ssh can be done easily, more advanced items like networking (with a farm of cloned machines) too. All this is free software.
A second option is to use a Raspi (3 at this time) to use a linux machine as the standard Software is based on Debian. So command line is available and — a little bit to my surprise — all standard tutorials (written for Ubuntu too) work instantly. So I was able to setup a VPN-Server with an intranet using the standard (very, very good) DigitalOcean tutorials. This works identically on a full blown virtual server as it does on a little raspi.
Both options worked very well in succession, the students very fast had a good understanding and practical knowledge. Using or starting to administrate a real unix server which could be a common task should be no problem at all. Highly recommended.
(Comic by xkcd)