I went through this lot some time ago and reinterpreting the legislation for schools is somewhat challenging. I generally start with why copyright exists (to ensure authors or their licensed representatives get paid for their work) and move on from there. The best general rule of thumb is that you do not have the right to use it unless:

You created it.
You have paid to use it (or some one else has ie the school/LA)
It is explicitly being given away for you to use.
In all cases the creator usually retains the right to attribution and the other "moral rights" regardless of the state of the commercial rights.

The law, however, does allow the use of copyright material for educational purposes, review and some free social activities, though there is clearly a difference between playing a genuine DVD to a class and ripping a duplicate to give to pupils (the argument could be made that since a school is a business, doing so is counterfeiting - a criminal offense).

The ERA, CLA, PRS-MCPS Alliance and PPL all have pretty good websites which explain what their licenses cover.

I've also discovered that in our LA at least the licenses are managed by the Schools Finacial Services department, though the information doesn't appear to be very high profile!