Children across Europe are going back to school after 18 months of pandemic disruption.
But in many countries, there are concerns of a new surge in infections from the highly infectious delta variant of the coronavirus.
Unlike the U.K., Italy and Spain are maintaining social distancing and masks for students and staff.
Italy also requires teachers to show proof of vaccination or a recent negative coronavirus test, along with Turkey and Greece.
In France, where students headed back to school Thursday, face masks must be worn by pupils 6 and up.
Britain, which lifted nearly all pandemic restrictions on business and socialising in July, has among the highest coronavirus rates in Europe, with upward of 30,000 new cases each day.
Hospitalisations and deaths remain far lower than during previous surges, thanks to an inoculation campaign that has seen nearly 80% of people over 16 fully vaccinated.