The government has been criticised for failing to acknowledge potential disruption to exams and school trips in its coronavirus contingency plans.
The NEU teaching union said it would be raising concerns with the Department for Education after the government released its coronavirus "action plan" this morning.
Kevin Courtney, joint general secretary of the NEU, also criticised recent suggestions that larger class sizes could be allowed because of the virus – arguing that this could set a "terrible precedent" for relaxing regulations.
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It was reported over the weekend that rules around class sizes could be relaxed if there is a shortage of staff in the event of a widespread outbreak.
Mr Courtney said: "We see nothing in these contingency plans about school trips, nor the implications for exam season and the grading of schools by league table and Ofsted. All will be at the forefront of the minds of teachers and school leaders across the UK.
"The NEU will be raising these issues with the Department for Education so that no undue damage is done to our schools and their staff in both the short and long term."
He also said: “Schools have an important role to play, but we are concerned about suggestions in recent days that larger class sizes will be recommended for indefinite periods.
"These will benefit no one – a cramped classroom will not keep pupils safe, potentially doing more harm than good and arguably work directly against the ‘social distancing’ recommended in the action plan. It will not provide peace of mind for parents.
"Teachers will be angered at the prospect of an already strained service – with fewer teaching assistants in most schools – having to stretch further. For our members, this could set a terrible precedent, that relaxation of regulations is merely a stepping-stone towards a future norm which sets back the clock on safe and practical working conditions."
Exams regulator Ofqual said: "We are working closely with awarding organisations and the Department for Education to consider how to manage any particular risks to the smooth running of exams and assessments should there be a widespread outbreak of coronavirus.
"We will update our existing guidance to reflect any specific arrangements schools and colleges should put in place if required. In the meantime, students, schools and colleges should continue to prepare for the summer exams and assessments as usual."
The DfE has been approached for comment.