Students' grades in the UK will again be assessed by teachers after GCSE and A-Level exams were cancelled for the second year in a row.
Education Secretary Gavin Williamson on Wednesday said the government would be "putting our trust in teachers rather than algorithms".
Mr Williamson vowed not to repeat the chaos of last year, when pupils complained they received unfair results under a computer-based model.
He said it was no longer feasible for formal exams – used to determine entry into university and college – to go ahead with so much time lost to the pandemic and the latest lockdown.
"Although exams are the fairest way we have of assessing what a student knows, the impact of this pandemic now means that it is not possible to have these exams this year," he told parliament.
"We will provide training and support to ensure teacher-assessed grades are awarded fairly and consistently across the country."
Cambridge International Education, which accredits IGCSEs, expected overseas exams would still go ahead.
"We work with schools in 160 countries and most of our schools are telling us they want to run exams in March 2021 and June 2021 and expect to be able to do so, in line with guidance from their national and regional authorities," a spokeswoman said.
“We continue to prepare for the March and June series to go ahead and are providing a range of measures to help our students and schools manage the impact of the pandemic."
She added: “With regard to our schools in the UK, we will be working closely with the UK Department for Education and Ofqual and will update those schools as soon as possible."
International schools in the UAE had been calling for answers on alternatives to written exams prior to Wednesday's announcement.
Many school principals in the Emirates told The National they were expecting a repeat of school-assessed grades.
Meanwhile, Mr Williamson said exam regulator Ofqual would be setting out its plans for teacher-assessed grades in the UK in the weeks ahead.
Geoff Barton, from the ASCL head teachers' union, said it was a "dereliction of duty" ministers had not already prepared an "off-the-shelf Plan B".
“Ofqual now faces a race against time to come up with the fine-tuning of a credible alternative to exams," he said.
Shadow Education Secretary Kate Green accused Mr Williamson of allowing "chaos and confusion" to reign by failing to listen to the "expertise of professionals on the front line".
Last summer, Mr Williamson abandoned algorithm-determined results in favour of teachers' predicted grades after a public outcry from students who felt they had been marked too low.
Earlier, Prime Minister Boris Johnson stressed that he would be “extremely cautious” over when schools would reopen.
“Schools were the very last thing to close, as I’d always promised that they would be,” he said.
“When we begin to move out of lockdown, I promise that they will be the very first things to reopen. That moment may come after the February half-term, although we should remain extremely cautious about the timetable ahead.”