David Benson, of Kensington Aldridge Academy, said if whole year groups are sent home in the run-up to exams, this should be taken into account by exam boards when their work is marked.
It comes after the Government announced most A-level and GCSE exams in England next year will be delayed by three weeks. The 2021 exams will go ahead, but the majority will be pushed back to give pupils more time to catch up on their learning following school closures.
Mr Benson said exams should go ahead because they are the fairest and “least worst option”.
But he added: “The Department for Education could outline a process whereby schools that face the worst disruption this year, for example having to isolate a whole Year 11 cohort, can receive extra consideration from exam boards when the time comes. The 2021 papers and grades will also need to be prepared fairly.”
There are fears poorer students will be disadvantaged because many could not learn remotely in lockdown.