Oobi and Kako join a singing group at the community center! At first, they fool around and don't want to sing what everyone else is singing. The singing teacher, Maestru, helps Oobi and Kako understand the benefits of singing along with everyone else. The boys sing a "round." — NickJr.com (source)
Oobi and Kako are listening to the radio. They hear an old opera song called "Yo To Ho" and sing along to it. Grampu walks in with the mail and shows the boys an invitation to join the community center. The boys want to join the center's singing group and ask Grampu if they can go. He happily agrees to take them. At the community center, they find Maestru, who is trying to teach his students Ray and Mimi to hit the right note. Grampu asks if Oobi and Kako can join the group. The boys loudly sing "Yo To Ho", which annoys Maestru. He reluctantly agrees to let them join, and Grampu leaves.
The boys learn their first song, "Row, Row, Row Your Boat". Maestru asks them to sing it in a round style. The boys sing "Yo To Ho" instead, and Maestru screams for them to stop. He tries to get Oobi and Kako to follow his instructions, but they don't. He tells Ray and Mimi that they'll take a short break so he can have a talk with the new recruits. Maestru explains to Oobi and Kako that they're part of a team now and can't just sing whatever they want. Kako asks if they'll sing "Yo To Ho", and Maestru says no. The boys disappointedly agree to sing "Row, Row, Row Your Boat" instead. The interview segments start, featuring Uma and some kids talking about music.
Oobi and Kako sing the song perfectly. Maestru is proud of them and asks the entire group to sing. The boys start to sway to the music, and Kako asks if they should stop. Maestru tells them that it's a nice touch, then asks everyone to sing and sway. As they do, Grampu comes back to take the boys home. He and Maestru clap for the singers and invite the viewers to do the same. Ray and Mimi ask Oobi and Kako if they'll see each other again next week, and the boys assure them that they'll be regular members from now on. The episode ends.