Ever since Stanley Lambchop was flattened by a bulletin board, each day brings new adventures! Stanley's second grade teacher, Ms. Root, loves science, and she has an exciting surprise in store for the class: they're getting a pet! Stanley and his classmates can't wait to play with their adorable hamster, Cottonball, and learn all about animal life. But then Cottonball escapes! Stanley and his best friend, Marco, have some ideas on what to do to find her, but they'll need to work through their disagreements and overcome engineering roadblocks to construct the best solutions for Cottonball. Will classroom 2E be able to catch her? And how will they keep her from escaping again?