Professor Haydn Hippo is a music instructor, conductor and toy mascot in the music class at school. He is particularly fond of the music of Franz Joseph Haydn. He can't climb stairs very well, so Clara Schumann-Cat kindly gives him a ride on her back, while he holds on tightly to her collar.
Professor Haydn Hippo is a replica of the character first introduced in Lesson Book 3. Suggestions are made in the Lesson Book for integrating the animals into the lesson.