http://wikipedia.org/

A giant; world-wide collaborative encyclopedia . Often criticised because anyone can edit it; but most people miss the point that this is what makes it so great. Shunned as a tool for student research, it does in fact make an excellent starting point, with articles that are usually up-to-date, well researched, accurate and comprehensive. It also provides a great vehicle for students to practice skills  of information literacy. Students can be asked to consider questions such as “What is the truth?”, “What is a reliable source?”, “Should we trust what we read?”, “How can we use references to decide if a source is reliable?”. Further, by having students contribute to Wikipedia, they can learn to appreciate their own knowledge, learn to work with others, and value being part of something bigger. I believe there is a nobility behind the Wikipedia concept that many people simply fail to see.

As all of the content on Wikipedia is licensed under a Creative Commons license, it is a great source for text and images that students can edit in the course of their learning and teachers can edit in the course of their teaching. As once example, there are many high quality maps on Wikipedia, which can be freely edited and incorporated into teaching resources.