Writer's Workshop: Getting Kids Excited About Writing by Maggie Hogan
This is a great resource for anyone thinking of organizing a co-op. This will take you step by step through the process of organizing, planning, and running your "Writer's Workshop". It does not, however, give any actual writing lessons. Many of the steps and ideas given are similar to what I use for a science co-op. But, there are many unique elements that only apply to writing. I have not been a fan of the WeE-books up to this point because of their broad generalizations. This one, however, is perfect for its purpose.