Two of Britain's largest teachers' unions have voted in favour of boycotting this year's national curriculum tests for 11-year-olds.
The decision threatens to scupper the tests – due to be taken by 600,000 11-year-olds in maths and English – in thousands of schools next month.
The move, which also puts this year's primary school league tables in peril, will present the incoming government with its first significant challenge as the tests are due to begin on 10 May, only four days after the general election.
Both the National Union of Teachers (NUT) and the National Association of Head Teachers (NAHT), who collectively account for 85 per cent of the heads in primary schools, registered votes in favour of a boycott in ballot results declared yesterday.
In the NUT's case, there was a 74 per cent vote in favour of a boycott. However, the turnout was only 33 per cent, allowing Schools Minister Vernon Coaker the opportunity to claim that most heads and deputies do not support the boycott. In the NAHT's case, the turnout was higher at 49 per cent, with 61 per cent voting in favour of a boycott.
Both unions claim the "high stakes" nature of the tests – which are used to compile primary school league tables – have led to too many primary schools teaching to the test in the final year of primary school, making lessons dull for pupils.
Mick Brookes, general secretary of the NAHT, said: "This is a significant result for the NAHT. We have not conducted a national ballot in a quarter of a century." He described the tests – known as SATs – as "a profligate waste of taxpayers' money" and indicated that between 6,000 and 7,000 schools would have to cancel them as a result of the vote.
Christine Blower, general secretary of the NUT, added: "We would like to see the next government introduce a national sampling system for English and maths tests [for 11-year-olds]. A sampling system would give a national picture of pupil achievement without identifying individual schools or children.
"Parents would still find out how their child is progressing. Reports to parents would come from teacher assessment, as is currently done in Wales, Scotland and Northern Ireland."
Last night, parents put their support behind the teachers' claims that the tests led to increasingly boring lessons for their children. Caroline Morgan from Dorchester, whose 12-year-old daughter Isabella did the tests last year, said: "She is a pretty academic child but she had a really dull year. All they did was work towards the Sats exam.
Now she's in her first year of secondary school, she's really learning again. It's fantastic. I would be delighted if William – my nine-year-old – didn't have to do them."
Laura Warren, from Maidstone in Kent, is a parent governor of a primary school and has a 12-year-old daughter. She said: "I think a boycott makes it feel a bit strong. But I don't think the tests add anything for children in the final year of primary school."
Leaders of both unions will meet early next week to decide what action to take. If they sanction the boycott, as is almost certain, the heads will refuse to open the test papers and pass them on to pupils.
Mr Coaker urged the two unions' executives to "think hard over the next few days and to decide not to disrupt children's testing and learning".
"Heads and teachers don't just have a statutory duty to make sure tests go ahead but a professional responsibility to their pupils and parents," he added. "A boycott of this year's tests would not be in children's best interests,"
Conservative schools spokesman Michael Gove has said that the tests would be "here to stay" under a Tory government.
Explainer: What the vote means
Q. Does this mean my child's test will be cancelled?
A. Not necessarily. The NUT and NAHT only account for about 85 per cent of primary school heads. Those who voted against the boycott may feel obliged to carry out the tests. It is estimated that between 6,000 and 7,000 of the 16,000 schools involved will scrap them.
Q. Will my child's future be affected if they don't sit the tests and pupils at neighbouring schools do?
A. No. The tests are used to rank schools rather than children. Secondary schools already re-test pupils when they arrive in September because they do not trust the SATs results. These tests will determine what set your child goes into upon arrival at secondary school.
Q. Will the boycott definitely go ahead?
A. The two unions meet to decide what action to take early next week. Given the result of the ballots, it is almost certain they will sanction a boycott. The only other event which could halt it is legal action. Last year, the Department for Children, Schools and Families said such a boycott was illegal because it was a head's statutory duty to carry out the tests. But in the middle of an election campaign it is hard to see this happening.
Q. So what will be the effect of a boycott?
A. If between 6,000 and 7,000 schools are affected, it will almost certainly scupper the primary school league tables. There would be no point in running them with 7,000 schools' names missing.