A headteacher in Mansfield has told ITV News "it's not fair" to expect students to sit examinations next summer because they've had different class experiences due to the Covid-19 pandemic.
It comes as Education Secretary Gavin Williamson has announced special help for students in England including advance notice of some topics ahead of tests - as well as exam aids when sitting papers.
But many students, teachers and parents have said the new measures are too late and are calling for exams to be cancelled now as the pandemic has severely disrupted schools.
Headteacher of the Brunts Academy in Mansfield, Carl Atkin, told ITV News students have had a disrupted learning this year.
He told Education Correspondent Peter Bearne: "Even within our own Year 11, we have got students who have been in school for differing amounts of time, and therefore had differing access to education.
"It's just not fair to expect them to sit exactly the same examination."
Mr Atkin said: "It's fairly safe to say that students up and down the country, and particularly our school has lost a tremendous amount of learning - despite our best efforts during lockdown.
"Before the summer period our students lost five months worth of learning.
"We were running online live lessons, but they're just not the same as being in the classroom."
When asked whether he saw a rise in students' anxiety levels as a result of their learning during the pandemic, Mr Atkin said: "There's a tremendous amount of anxiety amongst the year group."
"They are worried about the impact of their grades on their long-term future."
Analysis from ITV News Central Education Correspondent Peter Bearne
So now we know. GCSE and A-level exams will go ahead next summer, and the government insists they will be fair to everyone.
It should come as no surprise that the Education Secretary and South Staffordshire MP Gavin Williamson has taken this decision.
He's staked his reputation on ensuring the 2021 exams would go ahead, just as he did over the return of schools in September.
After much discussion with the exam regulator Ofqual, based in Coventry, the government has come up with the following measures designed to help students perform to the best of their ability.
There will be more generous grading
Students and teachers will get advance notice of some of the topics they will be tested on
Additional exams will be laid on in July for pupils who miss any due to illness or self-isolation
There are still many though who remain unconvinced. Many who ask how can a GCSE student from Cornwall, who's had minimal disruption to their learning, not have an advantage over one in Leicester who's had repeated spells out of class?
Even within individual secondary schools, some Year 11 students have had much more time in self-isolation than others simply because of where they were sitting in the classroom.
Headteacher Carl Atkin, from the Brunts Academy in Mansfield in Nottinghamshire, is one of those who believes the latest concessions still don't make up for the time students have lost. He wants the exams cancelled and the results based on teacher assessed grades as happened this year.
There is no perfect solution. But these are young people's futures at stake, and understandably many teenagers are suffering emotionally and physically because of the anxiety.
The one thing schools and parents have been crying out for is clarity and an early decision on the 2021 exam season.
That, at least, they have. It's now the job of students and their teachers to do the best they can in the months ahead even as the virus continues to disrupt our children's education.
Gavin Williamson tells ITV's Good Morning Britain it would not be right to cancel exams in England next year:
Mr Williamson unveiled a package of measures on Thursday to ensure that the grades students receive are as fair as possible following growing calls for the Government to do more to compensate for missed learning.
Students will be given aids, such as formula sheets, in some exams to boost their confidence and reduce the amount of information they need to memorise, as part of the measures.
A new expert group will be set up to look at differential learning and to monitor the variation in the impact of the pandemic on students across the country.
But it is understood that grading changes simply based on the region you live in have been ruled out.
Under new contingency measures, students who miss one or more exams due to self-isolation or sickness, but who have still completed a proportion of their qualification, will still receive a grade.
If a student misses all their assessments in a subject, they will have the opportunity to sit a contingency paper held shortly after the main exam series.
These tests are expected to run in the first few weeks of July.