An NASUWT survey found one in five teachers were observed more than six times last year. Even headteachers' associations admit that some teachers are being "observed to death" by heads due to changes in the way schools are assessed. The concerns have been exacerbated by schools using CCTV for classroom observation, a trend that follows a handful of cases last year where teachers were observed through two-way mirrors.
Members of the Association of Teachers and Lecturers and the NASUWT will say at their annual conferences that senior staff are using the new inspections regime, which relies more on self-evaluation, as an excuse to act like inspectors themselves. Observed lessons are often graded on a scale of outstanding to poor.
Mary Bousted, general secretary of the ATL, said she had met an Oxford graduate who was quitting teaching after only a year because she had been officially observed at least once every three weeks. "There is no doubt in my mind that self-evaluation has become self-inspection," Ms Bousted said.
"Lesson observation is often being done in a punitive rather than empowering way."
An NASUWT motion states: "This practice is yet another example of management bullying and is unprofessional." Newly-qualified teachers told The TES they had been observed as often as 11 times in the last term.
An English teacher at a secondary school in Norfolk said she was observed three times in one week and that three of four NQTs at her school were considering leaving. "I love teaching but the pressure is getting ridiculous," she said. "If you don't get a good grade you have to see the headteacher. I could spend more time worrying about observations than I do thinking about the teaching."
The concerns have been acknowledged by heads' associations who admit the practice has got out of hand in some schools.
Stephen Szemerenyi, an Association of Schools and College Leaders field officer and pay and conditions consultant, said: "Some heads don't know what it feels like, so some teachers are observed to death."
The ASCL has agreed guidelines with the NASUWT so its members should only observe teachers for a maximum of three hours. However, a more formal agreement on time limits for classroom observation is due to be discussed shortly by unions on the Reward and Incentives Group.
John Dunford, ASCL general secretary, said heads were under greater pressure to observe lessons because of the new inspections system which focuses more on lesson quality.
Maurice Smith, chief inspector, said it was part of school leaders' jobs to monitor and assess their staff's teaching. "The weight of that is up to schools to decide," he said. "Teachers' doors should not be closed."
Classwatch, a Hertfordshire company, has sold more than 50 CCTV systems to UK schools which record sound as well as colour pictures.
Managing director Andrew Jenkins said the company had initially stressed the security benefits of CCTV but had found that schools were as interested in using it to record lessons and help to improve teaching.
The NASUWT warned it would ballot for strikes if it proved that schools were using CCTV for official lesson observation.