For generations, students have flipped through their textbooks to amplify or clarify what they have heard in their lectures, to remind themselves how the various ideas relate one another, and — especially important in science courses — to find a good graphical depiction of the ideas they are struggling to understand. Once a student can picture in his or her mind the structure of DNA, say, or the mechanism of the greenhouse effect, much of the teacher's job is done.

Students will always need this kind of help; it is central to the learning process. But they might not be getting it from a printed textbook for much longer. The boundaries of the textbook have been stretching for some time now. Many already come with a CD attached, or include access to a website where updates and supplementary information can be found. Now those boundaries are threatening to burst entirely, as publishers experiment with making their textbooks available on personal computers, e-readers such as the Amazon Kindle and handheld devices such as the iPhone (see page 568). The printed textbook will not vanish anytime soon — but a generation from now, it could be just a memory.

There is a ferment of creativity and innovation in education that deserves to be encouraged.

Yet at the same time, new technology is not limited to delivering the same type of content in new formats. E-textbooks are part of a much larger technological shift in the nature of teaching and learning. As is typical on the Internet, it is users who are driving some of the most popular innovations. Although the large publishing houses are understandably taking their time to consider how best to connect to new media, teachers and students, unconstrained by the need to protect jobs and revenues, are further ahead in experimenting with how to make the best use of virtual environments.

At the simplest level is the worldwide trend for both teachers and institutions to provide online access to course notes — often free of charge. Beyond that are collaborations between teachers to produce altogether new types of learning resource. At the University of Edinburgh, UK, for example, teachers have produced a set of free-to-download computer animations that illustrate concepts and phenomena in the physical sciences (see http://www.ph.ed.ac.uk/cgi-bin/interactive/applets).

And at a third level are virtual classrooms, in which teachers speak to global audiences through online classes and seminars, or via do-it-yourself online courses such as those offered by the US National Science Teachers Association in Arlington, Virginia. Indeed, more and more colleges and universities are taking courses almost completely online through 'virtual learning environments' such as the commercial Blackboard system, headquartered in Washington DC, or the open-source Dokeos platform from Europe. These environments not only allow students to access tests, homework, grades and lectures via the Internet, but they increasingly use wikis, blogs, messaging and even three-dimensional virtual environments such as Second Life to create online communities around each course. Such communities are particularly valuable for distance learning, to avoid students having to work in isolation.

The result is a ferment of creativity and innovation in education that deserves to be encouraged. The funding agencies and private foundations are already doing so to some degree. The Edinburgh project, for example, was funded by Britain's Higher Education Academy, based in York. But they need to support such efforts more systematically — particularly by developing toolkits that make it easy for teachers to create instructional modules, and by encouraging the adoption of Sharable Content Object Reference Model and other such open standards for instructional software so that the modules can be used anywhere.

Textbook publishers would also do well to support such efforts, rather than ignoring or even resisting them, as the music industry tried to do with digital recordings. Textbooks were kings in a world where few other learning resources existed. University students, college libraries and school science departments had no option but to buy them. Now they have much more choice.