"One day I could give you the biggest classroom in the world," Edward R. Murrow told a former teacher he was trying to recruit to CBS as World War II ended. "I see CBS as an international classroom." Class was dismissed early at CBS. By the 1950s, the struggle between the profit motive and the cultural motive was long resolved in broadcasting. While the Internet is a very different medium from radio or television, its present stage of development can be compared to that of broadcasting a half century ago. Like radio and television then, the net is young and still subject to idealistic hopes like Murrow's.

With its "infinite" number of "stations," the net now has the potential to be the biggest classroom in the world. There are signs that the medium's opportunity is not being wasted. It is possible, for example, to find sites that go beyond the mere reporting of science news stories. Several of these disseminate good, factual biomedical information in a nonsensationalist way to a wide audience. One of the best is sponsored by the National Institute for Science Education (NISE), with funding from the National Science Foundation. NISE sponsors The Why Files, a "science behind the news" Web site that illustrates what the Web can do when it decides to entertain and teach at the same time. Nearly three years old, the site provides thoughtful, free access to dependable information about science.

Consider a recent Why File story explaining the background and implications of a report from Johns Hopkins about culturing human stem cells. The writing is clear and simple enough for a high school student to understand, but provides more explanations and is better written than many news stories.

The site's professional appearance stands out amid the cobbled clutter of many other sites. It looks like the product of a large, full-time staff, so I asked the Why Files editor and project coordinator, Terry Devitt, how large his staff is. "Tiny," he answered. He counted a writer who works a little more than half time, a half-time graphic designer, a technical consultant working 80 percent of a full week, and a few others who contribute some writing, research, administration, and marketing. These include Devitt, whose "day job" is science editor for the University of Wisconsin News Office, and others in the same office.

"We are ready to roll the information highway up to the schoolhouse door, but what's out there on the highway?" Denice Denton, former codirector of NISE and professor of electrical and computer engineering at the University of Washington at Madison, asked last year in a press release. If other sites follow the example set by The Why Files, there will someday be quite a lot out there.

The interest of the staff at NISE and The Why Files goes beyond explaining science to the public. "The Why Files also exists as a research project," Devitt said. "It is a platform to study the use of the Web and its efficacy in delivering popular information about science."

University of Wisconsin professor of journalism Sharon Dunwoody is studying how people use The Why Files. This work includes statistical analysis, surveys, and sophisticated social science experiments monitoring Web users in action. These test subjects might be drawn to stories ranging from what political polls can or cannot tell people, to why cows are scaring people in the United Kingdom.

Why cows are scary in the U.K. is the subject of a different but equally valuable site designed to provide unsensational, scientific information to the public. While The Why Files seeks to guide readers to better understanding of the science behind the headlines, a site like the UK Creutzfeldt-Jakob Disease Surveillance Unit lays out the facts almost like a reference book. In so doing, it provides an understandably jittery British public with extensive background information and updates on the real and imagined health risks presented by the appearance there of prion diseases such as bovine spongiform encephalopathy (BSE), or "mad cow disease."

One of the many hot topics on the Institute of Food Science & Technology site is, of course, BSE. The institute serves the public by providing extensive information on food safety, food science, and related hot topics in the news.

Both general science sites like The Why Files and specialized sites like those on BSE illustrate the range of what the Web can provide in terms of scientific information to the general public. And both help to weaken the barrier between science and the public.

In a speech delivered toward the end of his career as a broadcaster (indeed, it probably hastened the end of his career as a broadcaster), Murrow said of television:

The Junk Science Home Page - concentrates on "junk science" issues in the area of public health research. The tone is light and the criticisms are sharp and often well aimed. Produced by Steve Milloy, executive director of the Advancement of Sound Science Coalition in Washington, D.C.

The Lab - enthusiastically popularizes science for young Australians. Its explanation of "unscience" in advertising for hair and beauty products is a good example of successfully exposing misleading scientific claims in an area that interests the public. Produced by the Australian Broadcasting Corporation.

The MAD Scientist Network - with a similarly playful approach, the Washington University School of Medicine in St. Louis, Missouri, sponsors this "collective crania" of scientists who answer scientific questions from the public and link to some of the more than fifty other Web sites that allow visitors to "Ask a Scientist."