Technology now allows pupils to be taught by a "virtual teacher" who could be many kilometres away.

Notes can also be transmitted both ways

The process goes a step beyond video conferencing in that the hologram teacher appears to be in the classroom, and can see and speak to the pupils as if they were all in the same room.

The system was demonstrated by Edex, the largest supplier of internet connections to the UK education market, at the BETT2000 educational technology show in London.

Maths teacher Catharine Darnton was digitally teleported into the exhibition centre at Olympia from Graveney School in south London. The distance involved was only a few miles, but because the system uses internet protocols, audience and teacher could in theory have been anywhere.

Catharine Darnton: "Great potential"

It has been tested successfully within the school. Ms Darnton sees it as being of particular benefit for minority courses.

"I teach further mathematics. We've only got six candidates in the school doing that. The economics make those sorts of classes difficult to lay on," she said.

"But if you could have a single teacher being able to see three or four classrooms across a borough or something like that, then perhaps those sorts of subjects would be viable.

"And you could see the same sorts of things for minority languages - Latin and Greek - things that schools perhaps have not been able to deliver."

Duffie White: "Allows interaction"

The technology behind the hologram conferencing involves capturing an image with a video camera and loading it onto a PC encoding card.

The encoding card turns the image into a digital format which, with the help of some special software, is transmitted to another computer over the internet. At the receiving end, another computer reverses the process.

The developer of the system, Duffie White, says it is similar to videoconferencing in that video images are being transmitted, but users are not aware of looking at a screen and a camera.

Novelty perhaps, but students say they pay more attention than to a 'real' teacher

"You look at the people in the classroom, and the teacher appears within the classroom for the students.

"So the students aren't relating to a monitor, they are actually relating to a lifesize image of their teacher - and that teacher can see those students."

The key to the system's success is a fast internet connection - a normal phone line would not cope.

Edex has been pushing for some time for a fast national network for education, and argues that schools' use of ISDN connections is a blind alley.