“The adaptations were decided months ago,” said Sarah Hannafin, of the NAHT. “Our members are saying things have changed since then, there have been issues with staff attendance and student attendance. The problem is our members don’t feel this is enough.”

She said that the NAHT raised this issue with DfE officials and the exam regulator Ofqual before Christmas, and again more recently. It said their lack of action so far has been “frustrating”.

On February 7, exam boards will disclose to schools which topics are due to appear on test papers this summer.

Pupils should not be given so much information that they are able to memorise answers to write in exams, since this would give some an unfair advantage over their peers, Ofqual said.

Government ministers have said that exams are the fairest way to assess students’ knowledge, but said this summer’s arrangements must “take into account the disruption young people have faced over the past 18 months”.

The sweeping changes to the curriculum come after two years of exams being cancelled due to the pandemic.

In 2020, a controversial algorithm was initially used to calculate students’ grades, but this was eventually dropped following an outcry.

In 2021, teachers’ predicted grades were used once again, resulting in spiralling grade inflation for a second year in a row.

A Department for Education spokesperson said: “We understand the ongoing impact of the pandemic on students, which is why we set out clear plans for a wide range of exam adaptations to support students, which take into account expected disruption during this academic year.

 “Students will soon get information on the focus of exams to help their revision, as well as choices of topics in other subjects, and equation and formulae sheets in some GCSE maths and science exams. In addition, grading this summer will not return to pre-pandemic levels immediately, recognising the challenges they have faced.

 “At the same time, we have been helping schools to recruit supply teachers to manage staff absences, and provided more than 1.5 million laptops and devices for disadvantaged young people to learn remotely due to Covid.”