By Gary Eason
Education editor, BBC News website, at the NAHT conference
An education minister has been booed and hissed by head teachers as he tried to defend school league tables.
The main parties' politicians face the NAHT conference
Delegates at the National Association of Head Teachers conference also talked across Derek Twigg as he said tables gave parents like himself information.
The conference had earlier expressed a lack of confidence in the use of "flawed" value added data in tables.
Delegates also heard from Conservative and Liberal Democrat politicians - who each received rounds of applause.
The conference had listened in silence to Mr Twigg as he had outlined Labour's record on education, saying standards had improved.
But in the questions that followed the political presentations, Scarborough head teacher Dave Evans asked what each would do about league tables if they were successful in the general election.
"I'm a very strong supporter of league tables," Mr Twigg said - to boos and hissing from the audience.
Conservative spokesman Tim Collins acknowledged tables had been introduced by a Tory government. His party does not plan to scrap them.
But he said "a fair point" many heads made was that they should be judged not only on academic performance but on other things such as sport and drama.
There was sniggering when he said part of his party's plan to devolve money to schools included a publicity budget - so they could send out their own newsletters to their communities several times a year.
Liberal Democrat Baroness Sharp had told the conference her party would abolish league tables, as well as doing away with testing at the ages of seven and 11 - one of the points which earned her a round of applause.
Mr Collins' speech also went down well. He was clapped when he said every school would be grant-maintained, running its own budget, and that funding for the agreement on reducing teachers' workloads was inadequate.
He did not fare so well with his party's plan to have former head of Ofsted Chris Woodhead review the national curriculum.
He said he had heard "loud and clear" from teachers' conferences that the kind of things they had in mind for Professor Woodhead might not be comfortable "and in some cases might not even be biologically possible".
There was obvious discontent when Mr Twigg said schools would get no extra money to implement the workload agreement.
Richard Collins challenged the minister on the workload agreement
The conference had heard already from a string of heads who said they could not afford to give teachers the time out of lessons to which they would be entitled from September.
Questioner Richard Collins from Surrey wanted to know how giving teachers 10% of time out of the classroom for planning, preparation and assessment would "raise standards" when their absence would not be covered by other teachers due to lack of funding.
"I don't underestimate the challenge," Mr Twigg said.
Mr Collins said "unprecedented numbers of children" were in danger of not being taught by a qualified teacher - which was not what parents expected.
Baroness Sharp unwittingly also triggered a negative response when she used a word delegates had derided earlier in the conference - urging them to be "creative" about how they implemented the agreement.
League tables were sure to be a sore point, given the debate earlier on Sunday morning, which agreed that schools were being disadvantaged by the system and it should be changed.
Delegates queued up to complain about what general secretary-elect Mick Brookes called "dodgy data that's used to condemn us all".
There were particular concerns that the government published English test results for teenagers despite last year's marking fiasco.
This year's tests are going ahead as usual this week - using a marking system which the QCA exam regulator has said should be replaced.
One head teacher said: "The mess is happening again".
The conference also underlined its "disappointment" with the government's response to the Tomlinson proposals for reforming teenagers' learning in England. It called for a rethink.