It’s been literally half a century since the show began trying to teach little kids not only the alphabet song but also how the alphabet corresponds with letters in their lives. Now Sesame Street” has a library’s worth of pop song parodies about the alphabet, with A and C songs (as in “C is for Cookie”) among the most popular. And they’ve done dozens of original versions of the whole ABCs too. But just how do you reinvent a tune that’s as elemental as language? And how do you do it, over and over again, for a half-century?” – The New York Times