Kathleen Long Bostrom is a wonderful book introducing children to their first visit to church. It explains what happens and prepares them. My granddaughter goes to Sunday School but isn't aware that adults go to the church service. She tells everyone "I go to Sunday School and Mommy and Daddy go on a date."
A big thanks to Mason over at Thoughts in Progress. I won Rufus and Ryan Go to Church in a giveaway on Mason's blog.