In DePaola's (26 Fairmount Avenue) first book in a planned series, inspired by dePaola's beloved English terriers, excitement builds for twin pups Morgan and Moffat Barker as their first day of school approaches. Moffie, who was born 10 minutes ahead of her brother Morgie, takes her role as the "oldest" to heart, acting bossy, competitive and precocious. Her over-achieving manner initially earns her plenty of gold stars in Ms. Shepherd's class, but few friends. Morgie, meanwhile, finds his own understated ways to shine and makes several pals along the way. Before long, the siblings learn a few valuable lessons from each other and come to agree on one important thing: they love
school. DePaola's text introduces two amusing foils in Moffie and Morgie, but the story loses its delicate balance of humor and heart when Moffie's bratty behavior temporarily monopolizes the plot. Unfortunately, a few rough transitions trip up the story's rhythm and detract from the sweet denouement. Still, many of the situations here will strike a chord with young children and their parents and dePaola's sunny, gently humorous acrylic paintings are as winning as ever. Ages 4-7. (July)