Patricelli, author of several board books, graduates prematurely from cardboard to paper pages for this cheery birthday monologue narrated by a toddler who gets more play mileage out of a big box than the puppy it holds. Using bright, appealingly smudged colors and very simple, boldly outlined shapes, she depicts a diaper-clad child unwrapping the carton, hugging it in delight, then, accompanied by the puppy soon discovered inside, transforming it into an airplane, a ship and a robot before finally nestling down inside for a nap. The narrative voice is older than the child in the pictures, and next to Antoinette Portis’s Not a Box (2006), and several other takes on the familiar premise, this lacks the emotional range allowed by a longer format. (Picture book. 3-5)