Teachers and leaders “should not be seeking further work” from pupils to support their GCSE and A-level grades this year, the ASCL leadership union has said.

In guidance issued to headteachers, which seeks to pre-empt an expected government announcement on plans for assessments this year, the union said priorities for pupils in years 11 and 13 are “to ensure that they complete the curriculum in the subjects which they wish to pursue in the following year, not to add collateral to the assessment process”.

It was announced earlier this month that GCSE and A-level exams will be cancelled this summer and replaced with a system of moderated teacher assessments.

Some schools are setting work for pupils in anticipation of the assessments.

But in ASCL’s policy paper, deputy head of policy Duncan Baldwin said this was the wrong approach.

“On a practical note, ASCL would advise teachers and leaders that they should not be seeking any further work from students at this point to support teacher-assessed grades,” he said.

“Not all students will be able to respond; some will be ill whilst others will be living under more difficult circumstances at home.”

He also said it would be “wrong” for teachers to “give more students the benefit of the doubt by, for example, awarding more grade 4s than they might otherwise have obtained”.

“Awarding organisations and Ofqual will take steps to ensure that grade distributions resemble previous years. Where centres produce grades which seem particularly generous, a moderation process will be applied.

“Assuming that things head back to normal for the 2021 cohort, an inflated picture in 2020 would disadvantage those students currently in year 10 and year 12. They have enough to contend with having had their own studies disrupted.”

Baldwin said the system presented an “opportunity” for the profession to show “that it can, and will, produce reasonable grades through the process of teacher assessment”.

“For those who believe that the current system of examinations at 16 is inappropriate there is a chance here to show that an alternative universe is possible.”

ASCL is advising teachers should first consider what grade “would be the most plausible” if pupils were actually going to take the exam in the summer, then rank order the students within those grades, so that if the gradings need to be adjusted, then it is “clear which pupils would be affected, in either direction”.

This is a “difficult process”, Baldwin admitted, and “relies on teachers being fair and reasonable with their own pupils but also understanding the same process is being applied everywhere else”.

Finally, teachers should consider “whether the cohort of pupils and their grades taken together would be what you would have expected on results day”.

Baldwin added that there was “no need to rush”.

“What is important is that the process is well thought through and works in the best interest of students. We greatly appreciate that many of our members have their own ideas and concerns about all of this.

“We would like to reassure all of them that everyone involved is working hard and with great sensitivity to make this fair. Above all, this process will only work if the profession works together in a consistent, fair and ethical way. The students affected by this deserve nothing less.”

Ofqual is expected to provide details about how the teacher assessment system will work this week. Information about appeals and how the regulator will make sure grades are fair across schools are expected “by Easter”.