Early on in the run of Sesame Street, Jim Henson stayed mostly behind the scenes. He would voice various characters, such as Kermit, Ernie, and Guy Smiley, but he would be working off the scripts of others. The actual segments that he produced were a mix of traditional animation, live-action, and stop-motion animation. Among the few he did were the classic Number Song series, with music by Joe Raposo. Ten were made and each followed the same basic formula. The number was introduced, many examples of counting to that number followed, and it ended with a baker falling down the stairs because Henson likes his violent endings.
This man is doomed.
Through repetition and music and clear visuals, Henson captured the essence of educational television. While the show would expand and grow as characters developed and sketches became more intelligent and satirical, these simple moments would be repeated in shows to follow.
The idea of little songs about letters and numbers came about from the producers of Sesame Street after they noticed their children memorizing commercial jingles for products they did not care about, like coffee. One of the driving factors behind the show's creation was the insertion of these moments between the main stories. Instead of advertisements for products, children were being sold knowledge of the alphabet and the numbers up to 20. Hence, every episode was "brought to you" by these "sponsors."
It was subliminal messaging at it's finest.
So while we remember all of these silly songs about the letter C or the number 12 because they are catchy and fun, they also helped us recall this information without difficulty. The songs and sketches themselves have become classics in their own rights, regardless of (or because of) their original intent.
Another Family Guy joke makes sense now.