Cumulus the Cockatoo is a huge fan of the show, especially when it comes to beloved Elmo ... the world for his special singing and dancing routines. And when it comes to listening to music ...

Kelsea Ballerini is joining an illustrious list of music greats ... a singalong with Elmo and friends in a PEOPLE exclusive clip of her Sesame Street debut. "I wanna sing a song all about families ...