The tiny Raspberry Pi has been a popular system among hackers and educators alike. For $35, you get a fully functional PC to mess around with, program, and do what you like. If you own one and don't know where to start, you're in luck, as the system has gotten a free educational manual courtesy of a team of UK teachers from Computing at School.
The manual is licensed with a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 unported licence, which in non-legal speak means you can use, redistribute, change and copy. There's only one limitation: you can't sell it. There's lots of information in the manual, such as information of Scratch, Python, and the command line.
You can grab it from the Pi Store, or from this link if you don't have a Pi yet. Raspberry Pi would also like to issue a thanks to those who helped in the creation:
We want to say an enormous thank you to the whole CAS team, especially Andrew Hague, who corralled everything (and everyone) together as well as editing much of the document and writing a couple of the chapters. Thanks also to the team at Publicis Blueprint (beware! This link autoplays some video), who did more copy-editorial, production and typesetting work, all on a volunteer basis. Thank you to Graham Hastings, Michael Kölling, Ben Croston, Adrian Oldknow and Clive Beale, who wrote chapters of the manual; thank you to Bruce Nightingale, Brian Starkey and Alan Holt for the digital content. And thank you to the army of CAS members who worked so hard on reviewing and proofreading everything. Everybody who worked on this manual gave freely of their own time to make it happen, and we're very, very grateful to you all.