Malicious allegations were not the only contentious topic at the Association of Teachers and Lecturers (ATL) conference this week.
Members of the union also heard complaints that teachers in independent schools were being made to work illegally long hours without written contracts.
John Richardson, the ATL's officer for the independent sector, said heads could be tempted to sack teachers if their results were not strong enough, out of fear of complaints from fee-paying parents.
The union voted for homework to be scrapped in primaries, and for strict limits to be placed on how much can be set in secondaries.
Delegates also heckled a minister who said class sizes of 38 could be "manageable".
Jim Knight, schools minister, was asked by Malcolm St John-Smith, a teacher from Wakefield, about a colleague who was teaching 38 Year 3 and 4 pupils in a single class, without assistance. Mr Knight said teaching assistants could make such large class groups manageable. He later cited a school he had visited in Telford, which had 70 in a class.
But Phil Jacques, a Dorset teacher, was applauded when he told the minister: "Class sizes of 38 shouldn't be made to be manageable. They just simply shouldn't exist."
Easter conferences, pages 6-7.