In an interim report published this week, a task group commissioned by the Assembly government to undertake a national review into pupil behaviour and attendance also concluded that all teachers have received little or no training in tackling pupil unruliness and absenteeism.
Even local authority education welfare officers, according to the landmark report, have not been trained properly for their leading role in attacking discipline issues.
The report also includes a shocking estimate of the cost of an individual permanent exclusion to the local taxpayer in Wales of around Pounds 300,000.
Education unions were generally positive about the report's initial findings this week. But Gareth Jones, secretary of the Association of School and College Leaders, said positive action needed to be taken.
"In society generally there is less respect for authority and less parental control of young people and this makes the job of schools much more difficult. But good behaviour cannot be legislated.
"Schools must have the support of parents, other agencies and the wider community to change behaviour. The government's strategy will need to make parents' responsibilities clear. There are lessons to be learnt by work done in England and we hope the steering group will take those into consideration."
The reviewers concluded that despite lack of training, variations in exclusion policy between schools and too few opportunities for an alternative curriculum, "the majority of schools in Wales were orderly and well-managed".
However, the early submissions of the academically-led group suggest that new Wales-only legislation may be on the cards when the final report is presented next year.
The early findings of the National Behaviour and Attendance Review come after six months' work in "setting the scene" for more thorough investigations at school level over the next year.
The findings will pave the way for legislative reform.
But the report already identifies education for excluded pupils as a key area for possible reform.
According to the review panel, it is too difficult to compare children's behaviour with 20 years ago, although it is generally perceived to be worse.
It does concede that young people who come from chaotic, unstructured homes where children and adults quarrel with each other almost as equals is a problem at post-key stage 3.
But the report places more emphasis on the worrying aspect of rising non attendance in Welsh primary schools.
"Secondary absences are also much too high, with significant variations occurring between local authorities and schools throughout and across Wales," it says.
The task group also questioned whether permanent exclusions "really were helpful".
"We could look at the situation through a different lens and conclude that we in school lacked the skills, time and resources in helping himher to change hisher behaviour. Instead of taking a seemingly punitive approach and permanently excluding, we could simply set out to secure the help, resources, or placement he or she really needs," the report suggests.
The findings also appear to favour on-site centres in schools in managing behaviour. But it said some were resistant to this for fear of being labelled as "sink schools".
The paper also states that a serious assault committed in a school should be a police matter. The criminality of acts committed in schools will be considered in more depth in the review's next stage.
The working group will also investigate whether the delivery of full personal and social education lessons should become mandatory.
Widespread concerns were also cited in the report that initial teacher training does not equip new teachers to attack bad behaviour and truancy.
"Many young teachers leave the profession because they cannot manage pupils' behaviour and attendance adequately," it concludes.
KEY FIGURES INVOLVED IN THE REVIEW
Four working groups, consisting of 43 participants from a range of backgrounds, make up the review panel.
Teacher representatives include: Neil Foden - head of Ysgol Friar's, Bangor
Janet Kingston - head of Risca Community School, Caerphilly.
John Wagstaff - head of Ty Gwyn Education Centre, Rhondda Cynon Taff Borough Council.
Margery Brown - head of St Oswald's VA School in Pembrokeshire.
Peter Triggs - curriculum leader of design and technology for Bishop of Llandaff School in Cardiff.
Rhys Harris - head of Ysgol Gymraeg Treganna, Cardiff.
Sue Flavell - assistant head of Sandfields Comprehensive School, Port Talbot
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