Mac's pet Bitsy is the only robot puppy in the whole school.
Lilly bought him because Mac is allergic to fur, and couldn't have a live pet. But all the other kids tease Mac that Bitsy isn't a "real" dog. When a friend's beagle gets stuck on thin ice, however, Bitsy shows what a robot puppy can do, and forces everyone to reconsider what a real pet is.
Lilly's Clever Puppy is a story about a boy who is forced to challenge his preconceived notions, and who grows as a result.