You only need an airside pass to gain access to the restricted airside area.
All the other areas you don't need one.
So it really depends where the school is and what the policy is of the airport.
I have never had a pass as an instructor because we never operated on that side of the airport.
I really don't want to start on the internet telling you about the various ways you can get access without a pass to a restricted airside area but its not hard if your a pilot.