When teachers see a team of observers with clipboards, it usually means Estyn is paying a visit. But at one south Wales secondary it is pupils checking up on lessons in a bid to improve standards.
Nine pupils from Olchfa Comprehensive in Swansea have been sitting in on selected lessons for the past four months.
After each observation they submit written feedback on pupils' attention and behaviour, interest in the topic and response to tasks - and suggest how the experience can be improved.
Some teaching unions say the "pupil voice" is being taken too far. But English teacher Richard Jones, the school's Year 12 learning leader, said the initiative was about sharing good classroom practice rather than judging teachers' ability.
"We are not trying to trip teachers up or catch them out," he said. "The observation criteria are very focused. It's absolutely not about grading teachers and it's not another form of inspection.
"It is about developing a mature and insightful pupil voice. There is nobody better placed to talk about the learning in our schools than the learners themselves."
The idea grew out of an established scheme at Olchfa in which a team of teachers observe colleagues' lessons and give feedback on their teaching methods. It was set up as a "critical friend service" to make the best use of teachers' skills.
Mr Jones said the staff involved chose pupils they considered to be sufficiently insightful, intuitive and responsible to form their own team.
"They were given training and we discussed the importance of confidentiality and the fact they were being put in a very privileged position," said Mr Jones.
Some teachers had reservations about the idea, but so far 17 have volunteered to take part. Pupils only observe classes in their own year group or below.
Mr Jones said the scheme was an important extension of the concepts of pupil participation and pupil voice. The school has an active council and pupils sit on interview panels for teaching posts.
Nationally, pupil participation is at the heart of the Welsh Government's school effectiveness framework (SEF) and is a key part of Estyn's new common inspection framework.
But NASUWT Cymru accused Estyn of "misusing" pupil voice by supporting the involvement of school councils in staff appointments and in drawing up school improvement plans. It said pupils should be "nowhere near" that sort of decision-making as it undermines the teacherpupil relationship.
Rex Phillips, Wales organiser of the NASUWT, called the Olchfa scheme "outrageous". He said: "It's totally unacceptable for pupils to be observing teachers teaching in this way. They are not professionals and should have no role to play in lesson observation."
But deputy head Johne Cowley said: "We take the opposite view. We value and promote pupil autonomy. Some schools do it piecemeal but we are totally involved."
The pilot is due to be evaluated over the summer term, with the pupils and teachers involved interviewed about their experiences, before a decision is made about whether to continue.
CHILDREN'S VERDICT: `A brilliant idea'
The pupils who were chosen to take part in the pilot said they feel proud to be part of such an innovative scheme.
Olchfa head girl Tess Braunerova, who has observed two lessons so far, said: "I think it is a brilliant idea and a positive way of promoting pupil voice. It has really helped me understand more about how learning works, and how you can learn well in different situations with different teachers."
Year 9 pupil Katie Fletcher said: "I think that teachers with reservations should try to be part of the scheme because they would see it's not focused on teachers at all, but the pupils."