number of copies. more than 100 million copies worldwide. they ve been translated into 32 languages. the magic tree house series is written by mary pope ozborne, and on tonight s rock center with brian williams, nbc s meredith vieira explores how she captures the imagination of children the world over, like 9-year-old erin brullard. sounds like she means a lot to you. uh-huh. i really like the books. you heard it right. books. it wasn t a pop star or even a movie star who inspired this homeless third grader. it was an author. her name is mary pope ozborne, and her magic tree house chapter books are so wildly popular among 6 to 10-year-olds that as far as they re concerned, she is a rock star. [ chanting mary ] you are a rock star. their enthusiasm comes gushing out in fan letters. that one aaron wrote is just one