For politicians who view teaching unions as stubborn obstacles to reform, the criticism is always the same: narrow self-interest comes first, the quality of education a distant second.
In the UK, education secretary Michael Gove has effectively declared war on the classroom unions, which he derides as "enemies of promise". On the other side of the Atlantic, they are similarly under attack from the likes of the former Washington DC schools chancellor Michelle Rhee.
But unions are increasingly trying to wrest back control of the school improvement agenda. The National Association of Head Teachers (NAHT), which represents school leaders in the UK, has launched its own programme to raise standards.
The Aspire scheme was drawn up in response to complaints from struggling schools about growing pressure from the Department for Education, with many being warned that a poor rating from English schools inspectorate Ofsted could result in their being taken over by an external sponsor. The pilot scheme involves 20 schools across England, which will be given a three-year window - safe from government intervention - to improve standards and obtain a "good" rating from Ofsted.
During this period, the NAHT and private provider EdisonLearning will work with the schools' existing leadership teams to raise attainment levels. Extra support will be provided to develop leadership capacity, improve the quality and consistency of teaching, and enhance the collection and use of data.
One of the pilot schools, Greenhill Primary for 4- to 11-year-olds in Sheffield, was rated as good by Ofsted but last year slipped to "satisfactory" - the second-lowest category, which has since been renamed "requires improvement".
"It was a difficult time for us," headteacher Julia Brown said. "There's huge pressure. We were thinking, what can we do to improve? We thought we would benefit from someone outside coming in and having a rigorous look at what we're doing and help us see what's missing."
Ms Brown added that the NAHT is "not just arguing our case but doing something proactive to support us".
The involvement of EdisonLearning is likely to prompt concerns from some classroom unions, which have been outspoken about what they see as the creeping privatisation of state education. And there are still ongoing disputes and planned strike action by the biggest unions over changes to pay and pensions.
But Russell Hobby, the NAHT's general secretary, said the Aspire scheme is filling a gap and giving schools the support and wider network they need to improve.
The idea has won government backing, with Mr Gove saying he was pleased to give it his department's support. "I wish the project and those schools taking part in it every success as they seek to raise their performance to 'good' or better," he said. "I will be following this initiative with particular interest."
Meanwhile in the US, the two main teaching unions - the National Education Association (NEA) and the American Federation of Teachers (AFT) - have also been making strides in the field of school improvement. The AFT has created a Center for School Improvement offering "technical assistance, professional development and information". It has also entered a partnership with TSL Education, parent company of TES, to launch a lesson-sharing website for American teachers.
The NEA is also concentrating on low-performing schools, providing external support, resources and funding to drive up standards. "Today's education reform climate seems to focus on a misguided narrative of unions as obstructionists and educators as villains, ignoring how educators and their unions are leading successful reform efforts all across the country," the union said.