They are probably trying to tell yu that you should not steel things so people can trust you when you are by yourself and also when you are at your job and at other peoples houses also what they are trying to tell you that it is all about trustworthiness and also all a bout trust

trustworthiness

They are trying to let you know  that people  and them should trust you  and not to steel things just because they are not there and nobody is looking at you and that also you shouldnt use things that are not yours so they can leave you alone on things and also so they can trust you when you are alone at your job or at other places and never be worried about some things thst you are going to steel or use 

They probably want to tell yoy that you should always trust the people that you work with

do now

I think that the teachear shouldsheck all the computers and also check all the plugs from all the computers and if it is still not that then they should call an administrator and find out what the real problem is and make sure it doesnt happen one more time or that it occurs to any one else in the classroom or in the school