But with their complete silence as Nicky Morgan walked on stage, low cries of rubbish and then loud outraged laughter as she answered questions, head teachers here at the NAHT conference in Birmingham made clear quite how disillusioned they're feeling.
It's not just the plans to force all schools to become academies, which will affect primary schools most, as few have chosen to go down that route.
It's also the changes, delays and uncertainty around primary testing which have left the Department for Education looking ham-fisted.
The decision to postpone baseline testing for children starting school for a year, was closely followed by the accidental publishing of test papers for seven-year-olds online.
This all falls within the remit of schools minister Nick Gibb - so one head asked if he was running the department.  A question Nicky Morgan dismissed as "sexist" .
It's never great to have to start a speech with an apology, which the education secretary did today on the leaked test paper.
She offered significant reassurance that many schools won't suddenly find themselves marked down this year as a result of Sats tests.
But the speech, to a union which has tried harder than most to engage with the government, left them cold.
And these are the head teachers who are meant to be taking the initiative in deciding what kind of academy trust they want to form.
It would offer them greater freedom to make their own decisions, Nicky Morgan told them.
The loudest applause was for the head teacher who told her being forced to change wasn't the kind of freedom they needed.
It was at best an uncomfortable encounter, and ministers can and have been describing union opposition as coming from "vested interests".
Less easy to ignore are the many Conservative councillors and some MPs who are already very queasy about the forced academy plans.

His body was found on concrete steps in North Street in the early hours of Sunday morning.
He was treated by medical staff but was pronounced dead at the scene.
Gardaí (Irish police) have appealed for information about the incident.

Not sure what we're on about? Australia has run through a slew of prime ministers in recent years and is holding a federal election on 2 July. You can read more about Australia's revolving-door of political leadership on these links, but for now, let us journey to Australis Minor.
Are Australians ready to gamble on yet another PM?  |  Coup capital of the democratic world
Laurent Sanguinetti is a French-Australian illustrator who bases himself between Sydney and Paris. You can see more of his work at his website.

The 35-year-old former West Ham and Derby man was approaching the end of his contract at the club.
Bywater, whose previous clubs include Millwall and Sheffield Wednesday, has not played for the Brewers since signing on a free transfer from Doncaster in January.
But he will continue to act as cover for first-choice keeper Jon McLaughlin.
"It's great news that Stephen is staying," Burton manager Nigel Clough told the club website.
"He works very well with Jon McLaughlin, providing us with experienced cover, and has been a very positive presence around the club since joining."
With an audience of head teachers it was never likely to be a highly rowdy affair.
[NEXT_CONCEPT]
A man in his 50s has died after being seriously assaulted in Swords, County Dublin.
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On a far-off planet that's very much like Australia, strange creatures engage in a brutal battle for political domination, in this satirical cartoon from illustrator Laurent Sanguinetti.
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Veteran goalkeeper Stephen Bywater has signed a new one-year deal at Championship side Burton Albion.