They are observed by heads, other teachers, local authority advisers and Office for Standards in Education inspectors, students, researchers, consultants from the primary and secondary strategies and governors. If their school is in special measures, the attention intensifies, sometimes accompanied by conflicting advice. No wonder teacher union members are complaining.
But let's look back 30 years. When Callaghan gave the "Ruskin speech", which raised the idea of a national curriculum and of greater accountability, it was possible to teach for 30 years without being observed by any adult, let alone an HMI. Even headteachers often felt awkward about observing lessons, so powerful was the concept of a teacher's inviolable fiefdom.
Obviously, there must be a happy medium. Much of today's classroom observation is healthy and constructive. It has to do with sharing good practice and enabling teachers to examine aspects of their own work. Some is necessary monitoring because schools must be publicly accountable. And sometimes, criticism cannot be avoided.
But if classrooms are over-invaded - one unlucky teacher was recently observed no fewer than seven times in seven weeks - it is up to heads to protect them. The National Union of Teachers' guidance sensibly calls on them to avoid "bunching" visits, to limit their number, to clarify the purpose of all observations and to protect confidentiality. Fear of a sudden visit by Ofsted inspectors is leading, predictably, to over-preparation. Heads should ask themselves, is this observation really necessary? And, when teachers are under pressure, they should ask the same of LEA teams and other visitors, too.