Santhiapili Kanista used to share the classrooms of her school with 2,000 other children.

But today the desks and chairs have been moved out. Instead the bright, ambitious 17-year-old lies on a mat on the same dusty school floor with her mother, two brothers and two sisters.

In the past three weeks Sakkoddai secondary school, in Point Pedro, on the northern tip of Sri Lanka, has been transformed into a camp for 600 local people left homeless by the waves which swept the coastline of South-east Asia on December 26. Some 65 families now share the school’s classrooms; sleeping, eating and attempting to wash side-by-side.

It is a scene replicated across Sri Lanka and officials warned this week that it is severely hampering efforts to get all pupils back into classes by the end of January.

According to latest figures from the United Nations Children’s Fund (Unicef), out of 9,000 schools, 59 were destroyed and 102 were damaged by the tsunami.

A further 244 are now being used as temporary shelters for many of the 450,000 people still left without a home.

Pushpa Jayakody, Unicef’s head of education in Sri Lanka, said: “In some communities schools are the only buildings left standing and we cannot move families out of them - there is often nowhere for them to go.”

Aid agencies are trying to build tented camps for displaced families outside the schools. But where space cannot be found - some schools are housing more than 3,000 people - families will be left in schools and temporary classrooms will be built or tents erected for classes on school fields.

Martin Dawes, Unicef’s spokesman, said: “We don’t want to see displaced people removed from their community - they were heavily traumatised and moving them again will simply make things worse. It makes no sense moving people out just so their children can go to school. As long as we can educate the children, it does not matter if it is in a tent or in a classroom.”

It is feared that it could be up to a year before all families are moved from the 244 schools used as shelters.

Meanwhile, efforts were continuing this week to restock the 102 schools partially flooded in the disaster. Some 3,400 “school in a box” kits, emergency education rations, including pens and teaching aids, have been handed out so far by Unicef.

Attempts are also being made to address the problem of teachers killed or left homeless in the disaster. The education ministry confirmed this week that almost 8,000 graduates will be sent to help out in the worst-hit areas. Many are newly-trained teachers, while others are university graduates, prepared to act as makeshift classroom assistants until permanent staff can be found.

The only reminders of school life in Sakkoddai secondary are the blackboards still hanging on the walls and the odd desk left behind as classrooms were stripped to make way for the destitute people.

In this basic two-storey building set behind a small Catholic church, up to 10 families sleep in each classroom. All they have is a woven mat to separate them from the hard concrete floor. What possessions they could salvage, usually only a few items of clothing, lie beside them or are stacked on remaining shelves. They are often fed by aid workers in large tented areas in the centre of the school and collect cold water in buckets from distribution tanks to wash.

During the day the children play football and other games in the dusty, grassless yard, while the adults mill around the corridors and stairs.

There is little, if anything else, for them to do.

Santhiapili, who lost seven schoolfriends in the disaster, told The TES how she escaped her seafront home by fleeing out of a back door moments before the waves hit. She now fears she could spend months living in the school until her home is rebuilt.

“Seven families are sleeping together in one classroom,” she said. “It is not comfortable, we are crushed together and we have nowhere to bathe. But we are together, we are safe and we hope the water cannot reach us.”

What next for Sri Lankan schools?

See next week’s Friday magazine To donate to Unicef’s emergency education work in Sri Lanka, see www.unicef.org.uk