Jane Krauss asked this question on the wiki for the Office 2.0 conference, and I think it is a really good one. For me, it's an easy definition: Web 2.0 is the read/write web, where the contribution of the user is as much a part of the experience as receiving information. In my definition, that would include passive or "unconscious" participation as well (e.g., how Amazon can tell you what other books were bought by people who bought the book you're looking at, from tracking buying patterns). However, for education I like to focus on those Web technologies where user-generated content is at the core of the experience.
I'm including below a short essay I wrote on this recently. Comment MOST welcome and anticipated!
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"The Invasion of Web 2.0 in Education"
The Internet-based software programs that are generally referred to as "Web 2.0" may have been perceived, as recently as last Spring, as the latest pet technology of the educational uber-geek or the conference presenter. However, Web 2.0 programs are rapidly becoming tools of choice for a growing body of classroom educators, who are discovering that they provide compelling teaching and learning opportunities.
The phrase "Web 2.0" comes from the business world, and while it has the ring of a marketing catch-phrase, actually describes a significant transition in the use of the Internet, or the World Wide Web. Web 1.0, or the Web that most of us have been fairly used to using for some years now, has largely been a one-way medium: this is when we look for information on the web. Web 1.0 was the natural result of our existing mindsets of how information is transferred, and has been a reflection of our industrial culture: experts (or businesses) dispensing identical knowledge (or products) to mass students (or consumers).
Web 2.0 is a two-way medium, representing the next phase of the internet usage, and a change that (quite reasonably) has people making a comparison to the advent of the printing press--in Web 2.0 almost anyone can become a publisher, or a "content producer." In Web 2.0 the creation of material or information on the Web is as much a part of our experience as the finding or reading of data has been in Web 1.0. And in Web 2.0 the content created by regular users can be much, and sometimes almost all, of the value from a website.
Ask any teenager about their online experience, and while they may not know a detailed definition of the phrase "Web 2.0," they are certainly living it. An older generation may have hung out at the mall, but now youth depend on social networking sites like MySpace, Facebook, and Bebo for socializing--which are actually just frameworks filled almost completely with user-created content. Gone are the days of passing around the photos albums at parties (boy, does that seem like a long time ago). Now, digital photos (user-generated content!) zip their way directly from cameras to photo sharing sites like Flickr and Ringo, where the posted comments (more user-generated content) by friends are as much a part of the experience as the photos themselves.
For the last couple of years, the relatively small but dedicated group of educators that has always played with new technologies and brought them into their classrooms has been doing the same thing with the tools of Web 2.0. Early adopters of blogs, wikis, and podcasting have talked about the value of these tools in education for a few years, but now there is a growing swell of regular educators beginning to discover their power. As Web 2.0 tools in education gain wider adoption, they look less and less like a passing fad. Why are they becoming popular? Perhaps because the inherent ways in which these programs encourage collaboration and engagement resonates so highly with the pedagogical aspirations of teachers who are trying to meaningfully involve every student in something that is personally engaging for him or for her. And likely because these tools provide for great professional development for the teachers themselves, thereby introducing them effectively outside of the classroom and giving them a chance to: (1) discover the powerful learning potential they hold for themselves, (2) find examples of how other educators are using them in the classroom, and (3) connect with other educators who provide a virtual support community as they begin to implement new practices.
As Web 2.0 is then brought into the classroom, the very nature of student work changes. When a student's work is seen, and commented on, and collaboratively enhanced by a larger participative audience, those students are drawn into extended educational "conversations." In this way the relationship of the student to ideas and content are no longer constrained to the narrow avenue of interaction with their teachers, but they are suddenly interacting with their peers and others in the discovery, exploration, and clarification of knowledge. Sometimes that may appropriately be just be with an audience of their immediate classmates. Sometimes it can appropriately be with students and others all over the world. But either way, it involves the students in a very proactive learning environment.
While there are a lot of new Web-based programs that are often lumped into the catch-phrase "Web 2.0," not all of them provide for high levels of user contribution, collaboration, and "conversation." In this article we'll focus on the basic set of Web 2.0 tools which are accessible from the web browser and where the participation leads to conversation.