[Koha] Koha in schools, cataloguing teacher resources

Dear community, I have a situation where a school wants to catalogue their teacher resources but don't really want them to appear in an OPAC search alongside the 'regular' library items. I'm not sure that creating a separate library would be an efficient solution. I would appreciate any suggestions on how others have approached this situation. Many thanks, Clint. -- Clint Deckard Ashley Clinton RD1 Takapau Central Hawkes Bay, New Zealand.