In the park, Oobi meets a mom and a baby. He is fascinated. The mom explains how she takes care of the baby and lets Oobi help feed her, burp her, and play with her. Oobi gets to hold a baby for the very first time. — NickJr.com (source)
Oobi and Grampu are playing catch with a ball in the park. Grampu accidentally throws the ball into a nearby bush, and Oobi goes to get it. He finds it and starts to walk back to Grampu, but he's distracted by a weird sound. He spots a mom and her baby, who is making the noise. Oobi and Grampu walk over to the baby and compliment her. The mom introduces herself as Sheila and asks Oobi if he wants to play with the baby, Sophie. As Oobi says hi to her, Sophie starts to cry. Sheila explains that she's hungry and needs to be fed. Oobi takes a bottle from Sheila's bag and gives it to Sophie, who quiets down.
Oobi notices Sophie making baby talk, and he invites the viewers to join along by saying "goo-goo." Afterwards, an interview segment starts, where Grampu talks to preschoolers about baby talk. The scene cuts back to Sophie, who needs her diaper changed. Oobi helps Sheila change it, and they leave Grampu to take out the trash. Grampu is grossed out but reluctantly helps. Finally, Sheila teaches Oobi how to rock a baby to sleep. He rocks Sophie and sings her a lullaby, and she starts to snore. The episode ends with Oobi waving "goodbye" to the viewers while Sophie continues to sleep on his lap.