Having taken young children to the beach and playground in her Big Board Books, Krementz now follows them on adventures at school and on an airplane. Jamie and Katharine speak directly to their audience; and though these are not first experiences, each sensibly balances delighted independence with reminders of Mommy and Daddy. Specifics are explained through chronology: packing, security, boarding, meals, landing; teacher's greeting, parents' goodbyes, games and activities, snack, story, nap, reunion with parents. Katharine speaks like a three-year-old; readers will identify. Jamie looks too young for his occasionally sophisticated vocabulary (""safety procedures""; ""terminal""), but children will stay with it, picking up the proper terms early. One wonders why, however, this preschooler gets an adult airline meal--as well as why other Random House franchise-related products are flashed now and then. Most boards have two or three photos, all well composed, a-splash with hearty color, joyful, and caring. Jamie and Katharine's love for flying and school will be contagious, just as Krementz intended.