Before it was called Nickelodeon [wiki], the TV channel was actually called Pinwheel. Buzznet has the video clip:
Some of you may remember Pinwheel, the children's television show that aired from 1979-1989 on Nickelodeon. However, did you know that until 1981, Nickelodeon itself was also called Pinwheel?
Pinwheel featured live action segments between humans and puppets as well as animation from around the world. Some of the characters were Plus and Minus, Sal and Smitty and Jake. There were a total of 260 episodes of the show, the largest number of episodes a show has had in Nickelodeon history.
You can now catch it on YouTube. My 6 year-old loves it now too.