每日英语：In the Future, Who Will Need Teachers?

Guitar teacher Erich Andreas works from a basement studio in Nashville, Tenn. His classroom, though, is the world itself.

Across one hour, Mr. Andreas may be giving free video lessons to up to 1,500 people who stream his yourguitarsage.com broadcasts to points across the globe -- Chicago, London, Bucharest, Manila.

The current hype is that ubiquitous Internet connections and tablet devices will emerge as a competitive threat to real-life teachers, kill the textbook business and bring low-price learning to billions around the world.

Such big changes may take a generation, as problems at many for-profit colleges are showing today. But these forces are already at play, in full smashup glory, in what has happened to the simple guitar lesson.

The Internet already has devalued some musical knowledge -- musicians have been swapping song cheat-sheets on the Web for 15 years. Cheap and easy-to-use online video and a new generation of teaching apps have refined and broadened the scope for sharing similar know-how.

But, if the guitar world is any indication, we will still need the kind of teachers who stand in front of a room and talk. We will just need fewer of them.

'I don't know if in-person classes are really necessary,' says Thomas Sundboom, a 62-year-old guitar student in Balsam Lake, Wis., who is learning to play Creedence Clearwater Revival songs. He pays $40 a month for access to Mr. Andreas' site, less than half the $100 a month he paid for conventional lessons. 'That should put a downward pressure on prices, for sure.'

That's why this part of the $9 billion music-education industry shows what lies ahead for all kinds of education, both formal and informal.

There will be big business opportunities for a select group of star teachers and a handful of companies, too. The downside: Schools and teachers will have to adapt to lower-cost competition from around the country and the world. And they may have to acknowledge that technology might be better at many tasks done today by a fidgety teacher and a metronome.

'Traditional guitar teachers may find that the online approach will impact them significantly,' says Gary Ingle, executive director of the 22,000-member Music Teachers National Association. 'Right now there is a great sorting out period.'

The first transition in this marketplace is what is best called a 'media model,' in which a handful of personalities have become do-it-yourself broadcasters. They include instructors like the 43-year-old Mr. Andreas, who uses a series of free YouTube videos and live lessons via webcam to draw students to his $40 monthly subscription plan. Today he has 170 subscribers.

On YouTube, the biggest teaching star by far is Justin Sandercoe, a West London guitar instructor who started a website in 2003 with text-only pointers for aspiring players.

In July 2006 he uploaded his first video to YouTube and later put in 12-hour days recording a catalog of instructional videos. Today he has 170,000 subscribers, and his meticulous, enthusiastic lessons have been downloaded nearly 130 million times.

This base of support has changed Mr. Sandercoe's life. He now flies around the world, paying for his travel by giving in-person lessons to his fans. He also occasionally does one-on-one sessions via online video -- at the very real-life rate of $100 a lesson. He says he earns a 'pretty decent living.'

'I can do it wherever I like now,' he says on a Skype call. 'I had personal experience with teachers who were terrible. I hope my lessons will kill off that kind of teacher.'

The business problem with such media models is that production can be ramped up only so much -- it largely relies on one person's available time.

Which brings us to the next step: the development of new learning programs that aren't media in any traditional sense. Using mobile broadband, graphics and cloud computing, they are real-time feedback devices that can listen to a student play and track how well she is following streaming sheet music.

One system under development by a small California company called Chromatik Inc. will allow students to follow digital sheet music, then submit a performance of that music to a teacher for review. The teacher will be able to digitally annotate the performance and send it back to the student. All the performances will be stored online.

Robert Hutter, managing partner at $65 million venture fund Learn Capital, says these new programs don't cut out teachers, but rather extend 'the power of the teacher to many more people in the same amount of time.'

Motivation and discipline still lie at the heart of becoming a good musician. And it is here that technology still falls short of a traditional teacher's care and attention.

In fact, technology in some ways makes the problem worse. Devices have made it so 'kids can't focus,' says Albany, N.Y., guitar teacher Jason Ladanye. 'They don't make kids the same way anymore. They don't see the value in doing the work.'

Mr. Hutter, the venture capitalist, says that problem is solvable. He cites new studies that show social-network interplay -- wisecracking banter among students -- unlocks a greater ability to retain knowledge. 'If you're learning and engaging in a social community, that lights up the brain. That is the magic of this moment.'

Over time, perhaps, the traditional guitar teacher may become less of a gate keeper of knowledge and more of a motivator of the distracted student.

Teachers will be coaches, not priests.