Teachers need to feel confident and empowered, Nasuwt says
Pupils are wrongly being used to interview prospective teachers and give feedback on how well they perform in class, a teaching union says.
The NASUWT teaching union says attempts to give pupils a voice in their school are being abused by head teachers.
Delegates have voted unanimously to support a motion for a ballot over industrial action where abuses of student involvement are identified.
Head teachers says canvassing student opinion can be very effective.
The government said pupils should play a part in their own learning but it was for schools to decide what those roles should be.
Student voice was developed in the early 1990s to allow pupils to participate in decision making with the idea that students with a greater involvement in their school community were better motivated to learn.
But a paper at the NASUWT conference in Birmingham suggests steps to improve student voice in some schools have gone too far.
It reveals schools are using pupils to answer questions about teachers' competence and to help interview them for promotions, which the union says is unacceptable.
NASUWT general secretary Chris Keates said the dossier was "littered with examples of demeaning, embarrassing and humiliating practice".
In one case, a teacher was labelled "Humpty Dumpty" by a pupil allowed to sit on his interview panel.
The teacher eventually got the job and taught three of the five students who had been on the panel.
"These pupils turned out to be poor behavers and low achievers who were being given these positions of responsibility as a motivational and self-esteem boost," the teacher wrote.
In another case, a teacher said they were "humiliated" after being asked by pupils to sing their favourite song at interview. They declined and did not get the job.
Ms Keates said many of the examples were grossly unprofessional and stripped teachers of their professional dignity.
"To be effective in their roles teachers need to feel confident and empowered to act with authority.
"Involving pupils directly in making judgments about the suitability for posts and competence in the classroom places these considerations in jeopardy."
Ms Keates added: "It is clear that too many schools are engaging not in student voice but in the manipulation of children and young people to serve the interests of school management and its perspective."
But Janet McIntyre, chair of governors at Christ Church CofE primary school, in north London, believes pupils play a valuable role in helping select staff.
At her school in Barnet pupils on the school council, aged nine and above, give candidates a tour of the school, ask them questions and rate them out of 10.
Pupils are given training and their questions are checked but the questions are their own.
"This doesn't replace the formal interview process. Most of our decision making is done on that," she said.
But she said the views of the pupils from the council played a part, especially where the interview panel had been undecided between candidates.
"Pupils take this very seriously and give us insights we would not get on our own," she said.
Prospective teachers are also asked to give a lesson, observed by other staff, and pupils are invited to give their comments.
Association of School and College Leaders general secretary Dr John Dunford said schools and colleges had put a great deal of effort into involving students.
"This can be through regular surveys of student opinion, student councils, whole-school consultations on specific issues, student interview panels and even lesson observations."
"Students are very astute, sometimes surprisingly so, at articulating what works well and how weaker areas could be improved, especially in the classroom."
But he said schools and colleges that involved students in giving feedback to adults had a responsibility to ensure students and staff received training.
"It is particularly useful to have student views about interviewees for teaching, student support, and senior leadership posts.
"Candidates who can't convince the students are unlikely to be very effective if appointed."
A spokesman for the Department for Children, Schools and Families (DCSF) said: "It is for schools to determine - with staff and pupils alike - the precise role or roles that pupils/student might play, and what support they need in carrying these out, and mechanisms for student views to be captured."
He said lesson observation by students might be one way of achieving this.
"The purpose of involving pupils is to improve how teachers pitch their lessons and make them engaging," he added.
"The purpose is not to see pupils' views being used to feed into performance management of teachers."