The Magician's Elephant Kate DiCamillo Candlewick Press, $16.99, 202 pages; ages 6-10 for read-aloud, 8-10 for reading to oneself The bedtime stories that seem to work best at engaging yet soothing a tired young person have three traits: A gentle story with ... A touch of fantasy and ... A peaceful, slightly repetitive tone that enfolds the child until slumber. Most of these stories are picture books, but Kate DiCamillo has managed to create a lovely one for school-age children in her new book, "The Magician's Elephant." The story begins, as many classics do, with a child living in hard circumstances.