After playing with her toy vehicles, Uma decides she wants to take a trip. She packs a small suitcase, and enlists Oobi and Kako to help make costumes of an airplane, a train and a boat. Uma rides these vehicles to the kitchen where Grampu has made a special snack for the kids. — NickJr.com (source)
Oobi, Uma, and Kako are playing with a set of model toys: a train, a boat, and a plane. They imitate the sound of a train and invite the viewers to join them. This gives Uma an idea: she wants to go on a pretend trip to the kitchen. She says that she'll ride on her train, boat, and airplane toys to get there.
Oobi explains that the toys are a bit too small and couldn't actually bring her anywhere. Uma is disappointed, but Oobi tells her that they can make their own vehicles with cardboard and paper. Uma jumps around excitedly and accidentally falls over. "Uma trip," she says. The boys laugh and start to make a train from a box.
The next scene is an interview segment, where kids talk about the trips they've taken. The scene cuts back to Oobi, who is putting the finishing touches on a paper boat and a cardboard airplane. When they're done, Uma is ready to take her trip. Oobi and Uma start to sing a song: "Trip Wow." Oobi pretends to be a train conductor and takes Uma to the living room in their train.
Next, Kako pretends to be a captain and brings Uma to the couch in the paper boat. Finally, Grampu dresses up as an airplane pilot and brings Uma to the kitchen. There, he's prepared a plate of brownies for the kids. The whole group sings a reprise of "Trip Wow" before they have their snack. Oobi steers his train to the camera and waves "goodbye" as the episode ends.