Carole Fairbairn, her husband Colin and 25-year-old son Tom were on holiday on Khao Lak in Thailand when the waves struck on Boxing Day. All three have been reported missing.
Teachers from Coworth Park school in Surrey, where Mrs Fairbairn was head from 1997 to 2002, said prayers for the family at a service on Sunday.
The Duchess of York told The TES: "Carole has been much loved and respected and we greatly admired her as a headmistress. Our prayers are for the safety of her and her family but as each day passes there is growing concern for their fate in this terrible tragedy."
Sandi Stephen, head of Coworth Park, said Mrs Fairbairn had been a vibrant teacher who took the school into the 21st century. Mrs Fairbairn moved to Bangkok last year to teach at the private Shrewsbury international school.
Hannah Tugwell, a teacher at the Marlborough centre for autistic children in Hoo, Kent, was also presumed dead after being swept from a beach at Khao Lak.
Jo Lee, another teacher at the centre who was holidaying separately, went missing but was found alive several days later.
A spokesman for Medway council, which operates the centre attached to St Werburgh primary, said: "It is still a very confused picture and we are very concerned. We don't want to give up hope."
Heather Gill, a learning support assistant at Neville Lovett community school in Fareham, Hampshire, was confirmed dead this week in Phuket.
The 42-year-old had been on holiday with her husband and 17-year-old daughter. Neil Dewhurst, head of Neville Lovett, said Mrs Gill had worked at the school for 10 years. "People who knew Heather felt better just for knowing her," he said. "She was a positive and enthusiastic person and had lots of good humour." Pupils were informed of Mrs Gill's death on Tuesday.
Susan Ford, head of modern languages at Withins high school, Bolton, and her husband, who were on holiday in Thailand, have been reported missing.
Concerns were raised shortly after the tsunami about the safety of a group of 15 English teachers holidaying together on the southern coast of Sri Lanka. But the British Council said all were found bruised but safe and that many were now assisting the aid effort at the British embassy in Colombo. Richard Lunt, the British Council's acting director in Sri Lanka, said: "They're pretty shaken. They've been through a horrible experience."
All members of a cricket team from Harrow school touring Sri Lanka returned safely. However, Julian Ayer, who travelled to see his 17-year-old son Spencer play, was killed in Galle.
Dulwich college's franchise school in the Thai resort of Phuket, Dulwich international, escaped direct damage because it is in the centre of the island.
It has been acting as a help centre providing shelter, food and nursing and its teachers have been assisting hospitals and the city hall. Graham Able, head of the London school, has helped to set up a joint relief fund and is due to fly to Phuket tomorrow.
Tilly Smith, 10, a pupil at Danes Hill preparatory school in Surrey, was credited with saving around 100 lives in Phuket after warning tourists on a beach that a giant wave was coming. She said she had been able to spot the early signs of a tsunami, including the way the water bubbled and the tide had gone out suddenly, because of a lesson by Andrew Kearney, her geography teacher As The TES went to press, it was estimated that 150,000 people had been killed in Thailand, Sri Lanka, Indonesia and India. The Foreign Office confirmed that 40 of the dead were British but said that it was highly likely that nearly 200 Britons had perished.
Bouquets were left outside Ilam primary school in Ashbourne, Derbyshire, in memory of Isabella Peatfield, one of the youngest British victims. The five-year-old had been on holiday in Thailand with her mother Kim and father Tristram, who survived.
Other young victims included Lucy Holland. The 14-year-old granddaughter of Richard Attenborough, the actor and film director, was killed in Phuket.
Teachers at King's school in Canterbury, Kent, where Lucy had studied, said that she had been a vivacious pupil with a wide circle of friends.
Charities estimate that more than a third of those killed were children.
Schools across Britain are holding assemblies and memorial services to commemorate the dead (see opposite).
Educational psychologists recommended that teachers involve pupils in fundraising and explain the geographical causes of the tsunami to allay fears that a similar catastrophe could hit Britain.