Dom Knowles may have been on holiday in San Francisco but he still had his lessons to deliver. So for a month he taught his classes in the UK before the sun had even come up on the American west coast.
Of course, he has technology to thank for his ability to teach across thousands of miles. Nor is this unheard of: teachers stranded abroad by the Icelandic volcano improvised lessons over the internet at the start of this term. The difference is that for Mr Knowles this is not a response to an emergency, but what he does all the time.
Mr Knowles is headteacher of Briteschool (the "British E-School"), one of a new generation of online schools that are growing in popularity. While he has taught from San Francisco, one of his colleagues regularly teaches from Brazil. "If I have got a reasonable connection I can teach from anywhere," says Mr Knowles.
Briteschool provides both primary and secondary education to home-schooled and expatriate children who want to follow the English national curriculum. It offers maths, English, science, French, Spanish, history and geography, and pupils can go on to take the International GCSE (IGCSE) in most subjects.
Although online schools vary widely, they share some characteristics. Lessons are usually taught via microphone or text, and teachers can start a private conversation with a pupil at any time. They also have some features in common with conventional schools.
They have timetabled lessons, and teachers can use PowerPoints and interactive whiteboards as part of the lesson. The difference is that pupils rarely, if ever, meet their teachers and classmates, and practical work such as science experiments must take place at home.
Paul Daniell taught in a state secondary school for eight years before setting up InterHigh, one of the first online schools, in 2005. The school now has 230 pupils, aged 10 to 17, and charges fees of #163;2,220 per academic year.
While the teacher may never meet the pupil face-to-face, Mr Daniell says that the advantage of online schools is that they can offer more individual attention than is possible in an ordinary classroom.
Although there are about 18 to 20 pupils in an average InterHigh lesson, the ability of the teacher to talk privately with any one child is one of its big assets, he believes. "It's more like a one-to-one relationship than a pupil-teacher relationship," he says.
For teachers, online schools have the attraction of offering flexibility in where they live. As long as they are able to access the school website during British working hours, they can teach.
Mr Knowles says that working in online schools is often a lifestyle choice, but acknowledges that it will not suit many teachers. Most jobs in online schools offer only part-time work. "If you are only teaching three hours a week, you have got to find something else to do," he says. "That is not what most teachers do."
Online schools may be in their infancy, but initial research suggests they can be surprisingly effective. A study by the US Department of Education published last year concluded that "students in online learning conditions performed better than those receiving face-to-face instruction."
Demand for online schools in the UK comes largely from two distinct sources: independent schools and local authorities. Both turn to online schools to find provision for children who are unwilling or unable - usually for health reasons - to be taught in an ordinary class.
Some parents turn to online schools after their child has been bullied in school. Others are expatriate families who want their children to get a British education. The parent of one pupil at InterHigh, who asked not to be identified, says she opted for online education after her son failed to settle at either a state or an independent school.
"It can replace traditional school without the child losing out too much if that style of schooling actually suits them," she says.
Teaching online may appear to present classroom management problems, but Mr Daniell says that online teachers rarely have to deal with bad behaviour or disruption. Online teachers cannot resort to detentions, but they can log misbehaving pupils out of the class. Mr Daniell says the result is classes are well-behaved, there are fewer distractions, and pupils get through twice the amount of work as in a normal lesson.
"There are no pencils being flicked around the room. There are no wasps flying around the room," he says.
Not everyone is convinced, however. John Bangs, head of education at the NUT, says that while online teaching could be a useful supplement to schools, particularly in remote locations, children will lose out by not having face-to-face contact with their teachers, or with their peers.
"Online schools, or schools that try to create a virtual vision of education that substitutes for face-to-face education, are a very poor substitute indeed," he says.
Children learning online could also lose out by not being able to take part in extracurricular activities. But InterHigh has tried to get around this by running online activities, including an annual school play, where the rehearsals and performance all take place over the internet. At Briteschool, pupils take part in online poetry recitals. Obstacles to playing sport over the internet are harder to overcome, however.
Some experts argue that online schooling will become more mainstream in the future, even if it does not entirely replace normal teaching. John Hackett, who runs an online social networking site, Learning Landscape for Schools, says: "I could envisage a time when students could in theory work from home and just go into school for tutorials."
Mr Hackett argues that the main issue holding back online teaching is not the technology, but the technical expertise of teachers. "Writing an online course is actually a very difficult, demanding thing," he says.
The rise of online teaching may demand that teachers become more tech-savvy, but the advantages of attending a physical school are difficult to replicate on the internet. All the signs are that online teaching will increase in popularity, but there as yet little indication that it will make conventional schools redundant.
230 pupils; tuition fees of #163;2,220 a year.
First College UK
30-35 pupils; tuition fees of #163;1,980 a year.
Briteschool (The British E-School)
Under 30 pupils; tuition fees from #163;2,325 a year.
There are also two larger online teaching organisations, which mainly provide for children that local authorities wish to teach outside school:
600 pupils; fees about #163;9.40 an hour.
Nisai Virtual Academy
400-500 pupils; fees about #163;2,500 a year.