More than 600,000 Palestinian children in Gaza have missed the past two years of school.

Instead of studying and socialising, they have been repeatedly displaced, fled air raids and shelling, and often spent their days searching for water and food for their families.

With the ceasefire reached last month largely holding, humanitarian officials are now working frantically to reopen dozens of makeshift schools.

UNICEF spokesman John Crickx said it is critical for children to return to classes as soon as possible, not just for basic education, but also for their mental health.

UNICEF estimates that more than 630,000 Palestinian children missed out on school during Israel’s war on Gaza. So far, only about 100,000 children have been able to return, Crickx said.

Separately, UNRWA, the UN agency for Palestinian refugees, is providing some education through contracted teachers for about 40,000 students.

Most of the UNRWA-run schools, which catered to half of Gaza’s children before the war, have since been turned into shelters for displaced people.

Lack of space is a key obstacle. Dozens of schools have been destroyed or badly damaged. Many are still being used as shelters for Palestinians who have been repeatedly displaced.

Even during the most intense fighting, there were some efforts in displacement camps and communities to keep children from falling behind, even as everyone struggled with bombardment, power cuts, and shortages of food, water, and medicine.

However, lessons were sporadic, and some families kept their children close, unwilling to risk letting them attend classes for fear of their safety.

UN agencies say they are struggling to assess the damage and determine the costs. With the ceasefire still in its early stages, reconstruction of Gaza has not yet begun, and UN experts say the process could take years and cost approximately $70bn.