A teaching union leader has made an outspoken attack on poor discipline in Scotland's schools.
Mr McKenzie says teachers are involved in a "paper chase"
The president of the Scottish Secondary Teachers' Association (SSTA), Alan McKenzie, said many staff covered up problems to protect school reputations.
He said that teachers did not have the tools to control classroom behaviour.
Mr McKenzie wants ministers to take a lead by stating what is acceptable behaviour and giving more encouragement to exclude certain pupils.
Speaking before an SSTA conference in Peebles, Mr McKenzie said: "I have a grave fear that teachers, when talking about the problems of indiscipline and pupil misbehaviour in school, tend to cover up because of personal fears and they think it puts the school in a bad light.
"I don't think anyone would deny that it is part of a teacher's professional duty to be in charge and to control classroom behaviour, but there comes a point where there are no tools to do the job and that is the problem at the moment.
"In the front line there are no real tools that work. There are a whole series of paper chases, referral systems and punishment exercises.
"We are not denying it's a teacher's responsibility to do those kinds of jobs. We are saying the tools to do the job are not good enough and are not properly in place."
He added that although the majority of pupils were well-behaved it was an "inescapable fact" that there was a "corrosive minority" of students who were impeding the education process.
"Every day classrooms are constantly disrupted by what is called low-level indiscipline, low-level misbehaviour," explained Mr McKenzie.
"This is happening for teachers, every day, every hour, and in every school in Scotland and it is that which grinds us down and which corrodes the general good behaviour of the rest of our class.
"I would like an open, honest debate about this so that we can somehow get ourselves on course because it's important for everybody."
Education expert Pamela Munn, professor of curriculum research at the University of Edinburgh, said that she hoped what Mr McKenzie had said would not undermine teachers in the classroom.
"The most recent survey I completed saw teachers talking about increases in all different kinds of misbehaviour," explained Prof Munn.
"Ranging from the relatively trivial of talking out of turn to the more serious - such as violent incidents.
"All these behaviours are going in the wrong direction.
"However, I don't think we should be underestimating the skill and commitment of the teaching force in Scotland in promoting good behaviour, sometimes in quite challenging circumstances.
"Teachers are very skilled in doing a difficult, challenging and also a very enjoyable job, when it goes well, and one wouldn't want Mr McKenzie undermining the teaching profession."
Two other education bodies felt the SSTA chief had overstated the problem of pupil indiscipline.
The convener of the Scottish Parent Teacher Council, Steve McCall, said: "I don't fall for this avalanche of bad behaviour - I don't believe that.
"There might be slightly more difficulties, or changes in society, and they may be behaving slightly differently but I don't think it's children behaving badly, I think it's children behaving appropriately to the society they live in."
The Headteachers' Association of Scotland's general secretary Bill McGregor added: "In some schools indiscipline is a serious problem, in many schools it's a fairly minimal problem.
"So we recognise there is a problem with discipline but I'm not sure it's a huge problem."