its possible that the cameras have been installed and haven't been turned on because they are a delibrate deterrant to the children (i.e. similar to speed cameras which don't have an actual camera!). however, in primary school that is a very bizarre situation!
also, it's possible that they wanted to install CCTV throughout the school (there is in our school) in the common areas and it worked out as proportionally only a little more expensive to install in the classrooms too and they may use them at some stage in the future.
however, I would very surprised and shocked if parents were not informed of their installation - full stop. is there a parents rep on the board of management?
as a teacher myself (not that you'd know it with this spelling and grammer at this time on a Friday night!!) I certaintly would not have a problem with CCTV in my classroom - in fact, it would be a useful tool with some behavioural issues (plus, theoretically I can't even speak to a student one to one in my classroom in case there's an allegation of abuse etc) but at primary level and with lack of consultation with the parents I would be very concerned.....