An American newspaper has courted controversy with its plans to publish league tables rating the performance of thousands of individual teachers by name.
The Los Angeles Times is to reveal the rankings of more than 6,000 elementary school teachers based on their ability to improve students' scores on standardised tests.
An American teaching union has condemned the move, describing it as "irresponsible and offensive".
The newspaper obtained seven years of maths and English test scores from the Los Angeles Unified School District, which is responsible for 891 schools for children aged five to 18 and a further 208 pre-school or adult education centres.
The Los Angeles Times has defended its decision to make the database public. It said the disparities between teachers' performance are known to educational officials, but "rather than analyse and address these disparities, they have opted mostly to ignore them". It argues that this means the most effective teachers go unrecognised, while ineffective teachers get no extra help.
The newspaper's website now includes a section called 'Grading the Teachers'. "The Times has decided to make the ratings available because they bear on the performance of public employees who provide an important service, and in the belief that parents and the public have a right to the information," it says.
Arne Duncan, the US Secretary of Education, said he supported the publication. "What is there to hide?" he said in an interview with the paper.
But teaching union United Teachers Los Angeles has called for members to boycott the paper. It said the database dramatically oversimplifies complex education issues and will create a skewed and unfair picture of the profession.
It also said that linking test scores to teachers' names is an intrusion into members' professional lives that will not improve students' learning.
AJ Duffy, the union's president, said: "We object to the tying of teacher evaluations to standardised tests and are supported in that belief by many prominent education experts in the US.
"The release of the Los Angeles Times' teacher evaluation database will create chaos at schools for parents who will be misled about their teachers. This will negatively impact morale."
Randi Weingarten, head of teaching union the AFT (American Federation of Teachers), told the paper that parents had a right to know how well their children's teachers are rated on employee evaluations. However, she disagreed with publishing data showing how individual teachers have influenced test scores, accusing the paper's methods of being "primitive" and "rudimentary".
More than 1,100 teachers have requested and been given copies of their value-added rankings in advance of publication. More than 100 have submitted comments that will be published as part of the database, the Los Angeles Times reported.
The influential McKinsey report on the world's best performing school systems published in 2007, pointed out that the main driver of the variation in student learning in school is the quality of their teacher.
But John Bangs, head of education for teaching union the NUT, said that publishing lists of teacher performance "would be a major and disastrous destruction of morale".
"I think publishing this database would have a major impact," he said. "Teachers out there are being put in stocks and being pilloried. You never know what unforeseen consequences are: it could mean more teaching to the test and a focus on the most biddable children."