A great way for heads to keep their fingers on the pulse? Or a licence to spy, intrude and harass? Drop-in lesson observations can be controversial. At its conference last month, delegates of the Association of Teachers and Lecturers (ATL) voiced doubts about the way they are being used and voted in favour of an investigation.

“I would have to question the motives of any head who continually goes into lessons,” says ATL head of pay and conditions Martin Freedman. “It isn’t an Ofsted requirement, and if formal observations are done properly there should be no need for drop-ins. They are very disruptive for teachers because they change the context of a lesson. We have also had reports of heads using drop-in observations to intimidate staff - there is clearly the potential for abuse.”

Part of the problem is a lack of clear guidance. While classroom observations for performance management purposes are limited to three hours per year, heads have the right to make any number of drop-ins. Unions argue that staff should be given an idea of how many visits they can expect, and even when. Heads say this would defeat the point of the exercise.

“The great thing about a drop-in is that it is not staged or prepared in advance,” says Richard Brown, head at Hackney Free and Parochial Secondary, east London, where off-the-cuff observations were highlighted by Ofsted as a key factor in raising standards.

“It is a chance for me to see what is really happening. I go into the classroom as unobtrusively as possible and the teacher should immediately feel supported. I might have a quiet word afterwards, but nobody feels threatened by that. It is a normal part of interaction.”

This is the kind of informal approach advocated by education consultant Chris Quigley. He doubts the value of performance management observations and says they may lower rather than raise standards. “When teachers feel they are being judged, it forces them to conform to expectations and that can be very limiting,” he says. “But it’s important that heads keep in touch, by popping into classrooms as often as possible. A headteacher going into a lesson should not be a big deal.”

In reality, in most classrooms a visit from the head is out of the ordinary. It changes the behaviour of the teacher and the class. It is one reason why schools are using cameras to record lessons. At Thomas Telford School in Shropshire, teachers use Star Lesson, a system that allows them to record, review and edit lessons, then send footage to senior managers.

Senior managers can also carry out observations via a live video link, making the whole process unobtrusive. “I sometimes observe lessons remotely,” says Paul Halcro, deputy head at Thomas Telford School. “If I were in the room, that would have an impact. But it is still important to go into the classroom. You do need to talk to children and to look at their books. It is the only way to get the whole picture.”

Observation guidelines

Have a lesson observation policy, laying out the rationale behind drop-ins.

Drop-ins should not count towards performance management, unless by prior agreement.

If you feel you are being singled out for an unfair number of visits, contact your union representative.

Star Lesson: www.lessonobservation.co.uk.