All pupils and students could soon be tested for coronavirus, the Welsh Government has said.
University students are already due to be checked for Covid-19 before they travel home for the festive period.
Now the body which advises the Welsh Government has said all school children, college students, teachers and staff should also be tested.
The Welsh Government said education and childcare were “key testing priorities”.
Students at universities are being urged to take a new rapid turnaround test, regardless of whether they have symptoms, before they travel home for Christmas.
All students in Wales have been asked to travel home by 9 December at the latest.
Universities are already trialling testing students before campuses empty for the festive holidays, but some have warned testing thousands of students 24 hours before they head home is not possible.
Ahead of reopening all schools in September, Education Minister Kirsty Williams said the risk to children, especially primary school children was low.
However new evidence suggests higher levels of infection and transmission in school based age groups “than previously recognised”.
Figures show about half of schools in Wales have had confirmed cases since the start of term, with pupils and teachers having to self isolate.
Now, the Welsh Government’s Technical Advisory Group (TAG) has advised ministers to consider asymptomatic tests in schools.
In its evidence review into Covid-19 and children under the age of 18, it said: “Consideration should be given to exploring the feasibility of mass asymptomatic testing programmes in school and college settings to enhance infection control and maintain confidence of students, parents and staff.
“The development of any testing programme should take into consideration background infection rates, the full spectrum of available testing technologies, the context of community, testing and balance of strategic priority and testing capacity.”
In a statement, the Welsh Government said: “All our universities are piloting asymptomatic testing using lateral flow devices and we are considering wider use for these devices across a range of areas, including schools.
“In the recent update to the testing priorities for Wales, education and childcare staff were given priority status.”