Teachers have been urged to "do the right thing" when they award GCSE and A-level grades this year and deliver them "dispassionately".
Ofqual chair Ian Bauckham said that while it might be "hard", teachers must not let their sympathies with individual students sway the grades they award.
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Speaking at the Confederation of School Trusts' (CST) conference today, he said: "The mark of professionalism for us as teachers and educational leaders is to set aside our personal feelings, not allow ourselves to be influenced by other individuals, or by our own aspirations or sympathies for individual pupils and make our judgements dispassionately and objectively – that is what doing the right thing really means.
"It can, of course, be hard, but it must be the right way.
"Teachers are, of course, among the most respected and trusted roles in society, and the level of public respect for them has only increased over the past year," he said.
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"That integrity, which is at the heart of teacher professionalism, means that teachers overwhelmingly want to undertake this year’s important work fairly and honestly. But they will also, quite reasonably, want to know that every one of their colleagues in other schools is acting with the same degree of integrity."
He said that, as accountability measures had been "set aside" this year, the core purpose of GCSEs and A levels was their "passport function", enabling students to go on to the next stage of education or training.
"If qualifications do not tell the truth about their holders’ abilities, that is not only eroding the value of hard-won outcomes for young people but actually we risk sending them to destinations in an FE, university, post-16 courses and training programmes which are not right for them, risking later drop-out and potentially [depriving] others who would have been better qualified and better suited for those destinations," he said.
Commenting on the speech, Leora Cruddas, chief executive of the CST, said: “School and trust leaders have gone above and beyond to ensure that education has continued during the global pandemic.
"In a second exceptional year, teachers and leaders are engaging in a responsible and professional way with the significant challenge of awarding qualifications in the absence of public examinations. We do not underestimate the scale and complexity of this task.
“The important thing to remember, as Ian Bauckham identifies, is that teachers are professionals, trusted by the public. Mr Bauckham is right to say that this means two things.
"Firstly, that professional judgement is not inappropriately influenced by those outside who may have a vested interest. And secondly, that it is undertaken following proper training and established policies.
"It is most important, in this year in which our young people’s education has been so disrupted, that they have confidence in the qualifications they receive. I have no doubt, no matter how difficult, that teachers and leaders will rise to this challenge.”