The ageless dePaola casts two of his own Welsh terriers in this carefully constructed series kickoff. When Morgan and his type-A older twin sister, Moffat, start school, he proceeds to make friends by sharing his dinosaur book, but doesn’t shine as a student, while she apple-polishes her way to a row of gold stars. The roles reverse at week’s end when Morgan suggests that Moffat and rival, Sally, put up a block tower together, rather than compete with each other, and then goes on to earn a star of his own when the teacher asks if anyone can name some dinosaurs. Besides building his story around personality differences and conflict resolution, dePaola has enlisted a literacy consultant, evidently to ensure that his prose is accessible to beginning readers. Which it is—delivering modeled behavior in light, positive ways, and fleshing out his puppy protagonists with artfully presented differences and similarities, he has crafted a tale that all brand-new grade-schoolers will effortlessly absorb and enjoy. (Picture book. 5-7)