On a farm-themed day, Big Bird teaches Zoe how to imitate farm-animal sounds, including a duck’s “quack.” When a real duck arrives and responds with “moo” instead of quack, everyone is surprised. The duck, owned by Old MacDonald, has “a case of the moos.” Zoe helps by encouraging the duck to relearn the correct sound. At the end, the song Old MacDonald Had a Farm is sung with all the animals.