Today there are vast numbers of textbooks and course material on almost every subject freely available on the net. Much of it has been written by educators and is subject to continuous review and revision. Net-based material can be upgraded immediately to take into account the latest events in the world (the uprisings in Tunisia and Egypt for example) in stark contrast to printed textbooks which can often be up to 10 years out of date. There was a case recently of schools using textbooks which referred to the Soviet Union as a major power in the world.
So why then do we still insist that children and students should use printed material and cast doubt on the validity of the net-based material? This could even save schools and students a lot of money and free up the teacher to adapt and create the materials they feel will best support the goals of the course they're teaching.
So here's a short video with David Wiley of Brigham Young University explaining the advantages of using open online textbooks: Education without limits: Why open textbooks are the way forward.