My favorite picture book is Flotsam by David Wiesner.
It is a wordless picture book about a boy who finds a camera on the beach. He develops the pictures inside and discovers new worlds beyond his imagination. Every class I have ever shown it to has loved it. It leads to wonderfully imaginative discussions and so many questions. The other day we were working on asking imaginative questions and I used this book as a starting point for a writing activity.
As I went through the book and the kids read it (or looked at it, but experienced it is probably the better description) I had them writing down every question that came to their head. At the end of the book, we had about a hundred questions so we began sharing them and discussing what questions would lead to new and interesting stories, and why. What about those questions were richer than the other questions? We concluded that the really rich questions led us to a background story that we didn't have, or that the book did not provide (purposefully).
With our questions in hand, we each chose one that would be a great place to explore, and then we tried to provide that background story. I let the kids choose their preferred medium for writing (for those interested, 18% went with pen and paper, 36% decided on Desktop PCs, and 45% went with iPads), and they produced some of the best writing they have done all year. At the end of the day, we had a whole series of stories that brought the original picture book alive in so many different ways. They were all from our imagination, and not the authors, but isn't that one of the great parts about reading and writing?
We get to create our own worlds, our own explanations, and our own background stories.... in short, our imagination is what powers literature and makes it so wonderfully wonderful...