To model book letters (because we know you must model every single behavior and strategy you expect in your classroom!) I started by responding in letter form to a book we'd read together. This is a book letter I wrote to my class about The Bee Tree, back in 2008. Wow, right? It's amazing what you'll find once you start going through your files!
I shared a copy of the letter with each student and they stuck it into their reader's notebooks as a sample. They loved getting a letter from their teacher, even though they all got the same one!
After reading another book aloud, I modeled writing book letters in front of the students. You really have to slow down your thinking to do a good think aloud; examine your thoughts and explain how you know what to do, and where your ideas are coming from.
Creating a list of sentence starters is helpful, too. You can check out the anchor chart I used to do this here, on a previous post about monitoring your comprehension.
This is a cherished letter from one of my lovely students, who was reading Because of Winn-Dixie.