Classroom bubbles and face masks are being re-introduced in Guernsey schools from Thursday 17 March.
The Education Department is bringing back the protective measures following a rise in Covid-19 cases in the bailiwick.
They were relaxed two months ago, on Monday 17 January.
Secondary and college students will have to wear face coverings inside school buildings, as well as all school staff.
Primary pupils are being encouraged to wear a mask, but it isn't being made mandatory.
Schools may also stagger drop-off and pick-up times to reduce the number of people in an area at once.
All primary classes and years 7-9 at secondary schools will return to classroom bubbles where possible.
States-run extra-curricular activities and clubs have also been suspended, as have whole school assemblies and in-person parents evenings.
Schools previously had to close because of rising Covid-19 cases in the bailiwick
Guernsey's Director of Education, Nick Hynes, says it's important to keep schools open and avoid disruption to students' education:
"This is undoubtedly a challenging time for education settings, which is also being experienced by other essential services and private companies, due to the number of positive cases at the moment.
A number of our schools and settings currently have staffing concerns and we all remain focused on managing disruption as a result of absences while maintaining our absolute focus of keeping settings open and delivering education."
He added that the restrictions will be familiar to students and staff, saying 'we are not introducing anything now that hasn’t been in place before':
"When we have had to revert to these enhanced measures previously, it has served us well so I’m hopeful that they can do so again as long as we continue to have the support of all involved in the delivery of education.
I am sure that will be the case so I again take this opportunity to thank all staff and the community in advance for working with us to ensure these measures have the desired impact."