A headteacher said some days it had been impossible to find teachers to cover all her classes as Covid continued to wreak havoc with staffing.
But as students return amid a landscape of face masks and testing, school leaders are determined to do all they can to keep pupils coming in for face-to-face lessons.
"Children do only get one shot at their childhood and we have to give them the very best that we can under the circumstances that we have got," said Imogen Senior, headteacher at St Benedict's Catholic School in Bury St Edmunds.
Before the Christmas break, many schools were forced to return to online teaching because so many staff were ill or self-isolating. Those schools that did remain open, found themselves fighting over agency staff.
Ms Senior said: "There have been days when just no one's available and we have rung all the agencies we know and there is no one.
"We did have parts towards the end of last term where we really struggled to keep up with the demand for supply teachers and we would have days when we were doing things like combining registration groups or having staff cover in ways that we wouldn't necessarily choose to do.
"That's a real concern that we end up in a situation where we cannot cover the classes with the right people. Because it's not just about having anybody in front of the class - it's about having the teachers that can really move those students on."
That determination to keep schools open is, in part, why they have been happy to tackle the logistical nightmare of giving every student a Covid test before getting them back in the classroom.
At St Benedict's, they tested 700 pupils in one morning alone - something the headteacher said had become "a fine art" two years into the pandemic.
At Notre Dame High School in Norwich, more than 1,500 need to take tests on site, in line with government guidance.
Its assembly hall has been transformed into a temporary testing clinic with school years gradually returning throughout the week.
Most students agree the measures - which also include compulsory face masks for secondary school pupils - are necessary, although some are less keen on the tests themselves than others.
"I don't mind it very much because it's only a thing up your nose," said 12-year-old Agata Blonkowski. "What's the big deal?"
Eleven-year-old Fin Mutti said: "It's not too bad but it is quite uncomfortable. You can have quite nasty reactions sometimes such as crying or sneezing which can be quite unpleasant. But it's necessary so we can continue with our learning."
For Michael Egbuniwe, 11, the aim is to be able to see more of his friends again.
"It's messed up," he said. "We can't interact with people we like any more and we need to be more careful.
"We will get through some day but for now we have to social distance and do all this stuff which is really tough.
"I don't really like it but it's better being with the people you like rather than being at home where you can't do much. Some day we will be able to play around with our friends and have more contact with each other."Brian Conway, chief executive of St John the Baptist Catholic Multi Academy Trust, which includes Notre Dame High, said the in-school tests were picking up some positive cases.
But he said the majority were coming through tests taken by pupils at home - something the government wants students to do twice a week during term time.