Martin Weller's latest book has been published in an open access online format (199 page PDF) by Athabasca University. "Metaphor provides a means... of considering ed tech that does not rely on a direct comparison with the existing model," he writes. "Metaphors, then, are key to how we think about, implement, practise, and evaluate education and thus the role that we see for technology within it." But also: "How ed tech is framed and presented is often manufactured to suit the needs of those with vested interests." If you want to play along while reading this book, you might want to visit his metaphor generator website. The book progresses through a wide range of metaphors, including some of my faves like 'MOOC as a newspaper', 'Edupunk' and 'open educator as DJ', giving each a good critical discussion. Audrey Watters is very well represented in the book, but missing is any mention of her role as "Ed Tech's Cassandra", though maybe the metaphors we give each other might be the subject of a different book.