School leaders have said pupils must not travel in to sit mock exams or other assessments, after reports that some pupils have been asked to come into school to do so.
Dr Patrick Roach, general secretary of the NASUWT teaching union, said that it "beggars belief" that some members were reporting that their school was asking pupils to take assessments during the coronavirus lockdown at school.
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“The government has been clear that schools are open only for the children of key workers and for those pupils who have been identified as vulnerable," Dr Roach said.
“Therefore, it beggars belief that some pupils are being required to travel to school to complete mock examinations and other assessments to support the process of producing centre assessed GCSE and A-level grades for exam boards."
He added that Ofqual and the Department for Education had confirmed there was no need for schools to set any additional assessment work to provide calculated grades for pupils, and that schools must act in accordance with government instructions.
"The UK is currently in the midst of a public health emergency and attention has rightly been drawn to those individuals who are putting their lives and those of others at risk by ignoring the measures that the government has put in place," he said.
"While the vast majority of schools are behaving sensibly in this respect, it is profoundly disturbing that some have decided that the lockdown provisions that apply to everyone else shall not apply to them."
He said parents of children who were asked to travel into school to complete assessments should ignore the requests and report them to the Department for Education directly.
"The union will also intervene robustly to protect any of its members who are instructed by their employer to participate in such reckless and wholly unnecessary activity," he said.