"Play Ball!" is an episode of Oobi from the first season.
Kako becomes frustrated with T-ball and refuses to play. After Oobi learns the basics of Kako's hand-clapping game, Oobi teaches Kako the fundamentals of T-ball. Kako gets a hit and we also discover that Uma is a T-ball natural. — ABC Television
Oobi and Kako are wearing baseball helmets. They prepare to play a game of tee-ball as they chant the phrase "Batter up!". Grampu sets the equipment up outside and lets the boys know that everything is ready. He shows them the bat they will be using and leaves to go watch the game. Oobi and Kako ask Uma to catch the ball after they hit it. Oobi steps up to bat first. He hits the ball, but Uma misses it. She picks it up and brings it to Kako, who takes the bat and tries to hit the ball. He misses and claims that he is just warming up. Kako tries again, only to become frustrated. Kako angrily puts the bat down and Oobi asks if he wants to try again. Kako quits and tells Oobi that the game is "silly" anyway.
He angrily enters Oobi's room and tells Oobi that they should play a hand-clapping game instead. Oobi does not understand how to play at first, so Kako offers to teach him. Oobi tries and plays the game successfully. Oobi gets the idea to teach Kako how to play tee-ball, similarly to how Kako taught him the hand-clapping game. Kako accepts and walks outside.
Meanwhile, Uma wonders if she will ever catch the ball. On the field, Oobi teaches Kako to keep his eye on the ball while at bat. Kako does this and swings. He misses, but Oobi tells him to try again. In a slow-motion sequence, Kako hits the ball successfully. Uma finally catches the ball and happily brings it to the boys. Uma asks if she can bat and Kako shows her what to do. Uma hits the ball, which lands on Grampu's face. He comes over to find Uma at bat . He appears very angry at first, but quickly changes his tone and tells her that he is very proud.
Later, Kako asks the viewers if they like to play sports. The next scene shows Oobi and Kako in the field again. They notice that their baseball helmets are numbered. This inspires them to play a counting game with the number 3. After the game, the characters give each other "high-fives." The episode ends.