The NASUWT Teaching Union is calling on ministers in Jersey and Guernsey to urgently reintroduce Covid safety mitigations in schools.
The plea comes as case numbers are rising, which appear to be driven by infections amongst pupils and staff.
Union members have written to States of Guernsey and the Government of Jersey to warn that without proper safety precautions in place, there is a risk to disruption to education as well as negatively impacting the welfare of school staff and pupils.
As well as calling for face coverings to become mandatory in all school areas, the Union is asking for a pause on whole school assemblies and in-person parental meetings, and the cancellation of all non-essential activities.
The Government of Jersey says the "Department for Children, Young People, Education and Skills monitor the Covid data in schools daily and advise and support school leaders in the regular review of their risk assessments for mitigating Covid-19".
The Government also pointed out that most of its educational staff have been double jabbed with some having their boosters.
It says the arrangements will be kept under review with officials meeting with school leaders and unions to explore the impact.