School banding shows best and worst performers in Wales
More than a quarter of Wales' 22 councils have no schools in the top band of a system which identifies the best and worst performers.
Secondary schools have been placed into one of five bands based on GCSE exam performance and pupil attendance.
In more than a third of areas, there are no schools in the bottom band.
The Welsh government denies the claims of teaching unions who say the rankings "name and shame" struggling schools.
Schools with the best scores are placed in Band 1, whereas those with the worst are in Band 5.
There are 27 schools in Band 1 and 28 in Band 5. Neath Port Talbot has the highest proportion of schools in Band 1 while neighbouring Bridgend has the highest proportion in Band 5.
Merthyr Tydfil, Powys, Torfaen, Blaenau Gwent, Monmouthshire and Ceredigion have no schools in Band 1.
At the other end of the scale, there are no Band 5 schools in Neath Port Talbot, Newport, Pembrokeshire, Vale of Glamorgan, Torfaen, Carmarthenshire, Conwy, Denbighshire and Flintshire.
Education Minister Leighton Andrews said: "If we are to drive up standards across the board in Wales we need to know how our schools are performing. Banding is at the heart of this.
"It's not about labelling, naming or shaming, or creating a crude league table. It is about putting schools into groups to identify which need our support and which we can learn from.
"You cannot un-invent the Freedom of Information Act - parents and pupils have a right to know what is best in Wales and how their schools measure up."
Anna Brychan, director of the National Association of Head Teachers Cymru, said a single grade could not represent the entirety of what a school does.
"We are especially worried that the achievements of schools in lower bands, particularly those that are improving year-on-year by focusing tirelessly on standards and relying on their staff and communities to go the extra mile, will go unrecognised," she said.
"This will damage the morale of the very people who are making a crucial difference to pupils' lives."
The banding system is being introduced as part of 20 reforms to drive up standards.
Plans to band primary schools are currently being developed, although it was revealed at least 30% would be exempt because they had too few pupils to produce reliable data.
Dr Stevie Upton, a specialist in Welsh school performance, said parents who are concerned about the results of the banding should use the information as a starting point for a discussion with schools.
"Many of the measures that are within this particular banding system are indicators that have been used for a long time already, they are things that schools will recognise," said Dr Upton.
"The issue of whether putting them together is helpful is another matter.
"But the simple fact is we have it now and we need to work out how to use it constructively."
Teaching unions claim the new system is tantamount to a return to league tables and accused the government of introducing a "branding system".
Branding by banding
David Evans, NUT Wales secretary, said teachers "strongly opposed" the process.
"This naming and shaming is something that we in Wales were proud to have moved away from, and it is a real shame that the government has decided to return to what is an outdated and restrictive practice," he said.
According to the Welsh government, the system's purpose is to identify schools in need of support, although extra funding will not be made available to schools in need of improvement.
Schools in the bottom bands will instead receive support from four new regional school improvement services, which will be run by groups of local authorities.
However, BBC Wales understands the support services will not be operational until September 2012. The Welsh Government says there will be extra support for councils in the meantime.
Dr Philip Dixon, director of the Association of Teachers and Lecturers Cymru, said the promised support for schools in the lower bands was failing to materialise.
"Schools want to know what new and extra resources they will have to improve their performance," he said.
"We are afraid that we could see the situation where schools labelled as under performing are just left to languish without any effective support.
"The government needs to act quickly if it is to avoid creating a demoralised workforce."
The Welsh Conservatives' shadow Minister for Education Angela Burns feared the new banding system could cause confusion for parents and "negatively impact on staff morale even in academically well-performing schools".
She added: "While accessible information on standards in our schools has the potential to be a valuable tool for parents, the Minister's current plans are not comprehensive and rank schools partly based on factors totally out of their control."
Ucac, the teaching union for Welsh language teachers, said the results would be misinterpreted.
The union's general secretary Elaine Edwards: "Although a complex formula using 12 different pieces of data is the basis for the results - schools are given a simple 1-5 score.
"The likelihood is that this impossibly oversimplified score will be used to measure schools' overall performance, and will encourage competition between them."
However, the Welsh Local Government Association (WLGA) responded positively to the banding information.
WLGA education spokesman Coun Peter Fox said: "Secondary school banding is about everyone in the education system in Wales working together to improve outcomes for children and young people, it is not about creating a school league table.