The story, which is set in a castle, tells the tale of a mouse named Despereaux who has big ears and a huge heart, a beautiful princess named Pea who is kidnapped, a rat named Roscuro who lives in a dungeon and longs for light, and a servant girl named Miggery Sow who wants to be a princess.
Each character is introduced separately in a story of its own but as the tale unfolds the stories and characters weave together. A lyrical book, it deals with time-honoured themes such as good versus evil, light versus dark and unrequited love.
As Ms DiCamillo reads the opening pages, it is easy to imagine a tiny mouse wandering the high-ceilinged corridors of the castle and rats scurrying in the dungeons below. The P4 class from Davidson's Mains Primary in Edinburgh hang on to every word, some with mouths ajar, others with eyes open wide.
Since the book's launch in September, it has sold 500,000 copies in the United States, where Ms DiCamillo is a well known author. It has been on the New York Times bestsellers list since November and in January was awarded the 2004 Newbery Medal, the highest honour for a children's book in the US, given by the American Library Asssociation.
Ms DiCamillo's previous two novels have also won awards. Her first, Because of Winn-Dixie, was one of the 2001 Newbery Honor books and The Tiger Rising was a National Book Award finalist.
In between reading extracts from each of her books, Ms DiCamillo asks her audience if they have any questions. Hands stay down until she asks them a few. Do they like reading? Lots of hands go shooting up in the air. Does anyone want to be a writer? Five hands go straight up. Then when she asks what books they like reading, a full-scale discussion begins. Names of authors are thrown around - Jacqueline Wilson, Beatrix Potter, Roald Dahl, Enid Blyton - as are titles of favourite books.
A common theme running through Ms DiCamillo's books is animals: they are about a dog, a tiger and a mouse, respectively. "I'm pretty obsessed with animals," she admits.
"I grew up in Florida and when I was 30 I moved to Minnesota," she says as they talk about her first book. "It was cold there. It was the coldest winter in Minnesota and I wanted to move back home, but I couldn't afford to and so through my imagination I got to go back to Florida.
"It was also the first time I didn't have a dog, so I made one up. That's the fabulous thing with writing; you can make things up that don't happen in real life."
"How old were you when you started as an author?" a boy asks.
"When I was in college I got the idea that I wanted to be a writer, so I was about 20. My tutors said 'You have got a way with words.' And I thought 'Oh fabulous, I'm going to be rich and famous.'
"But when I was almost 30 I realised I was never going to be a writer unless I did one thing, and do you know what that was? To write something.
I'm 40 now so I've been at it for the past 10 years and I've been making a living of it for the past three years."
As the session comes to an end, nine-year-old Rachel, who wants to be a writer, says: "I really liked it when she read the stories. I want to read all of the books now."
Andrew, aged eight, agrees. "We have read the whole of The Tale of Despereaux and some of Because of Winn-Dixie and I want to read the other book now. I would definitely recommend them to other people."