Security

I can see the reason for having students limited especially if you are talking about naturally curious teenage students, that will tend to play around and snoop untill they crash your systems, I cannot see why the Techs and teachers need separate user accounts if they both have the same access privileges i.e they are both part of the administrators group, if the teachers where to have lesser privileges than the tech's then they should be degraded to a group with lower privilegees such as power users, however if not then two groups would suffice.