This is an episode of Super WHY.

Today is Whyatt's birthday, and Whyatt asked for a big party. But his family is being very sneaky and he doesn't know why. To figure it out, The Super Readers fly into the book The Twelve Dancing Princesses, where twelve ballerinas throw a surprise party for their father, the king's birthday. Whyatt realizes that if the ballerinas threw a surprise party for the king's birthday, the same thing happened on HIS birthday.