CCTV monitors classrooms at one in 14 schools, according to a survey.
The poll of teachers also found that almost a quarter feared there might be more cameras hidden around the campus that they did not know about.
Most said their schools were fitted with surveillance cameras. Almost 80 per cent said there were cameras at the entrance and more than 7 per cent said there were some in classrooms.
Nearly 10 per cent of teachers polled by the Association of Teachers and Lecturers said there were cameras in the lavatories.