This article first appeared on Mashable.
A, B, C — 1D. Well, that's not quite how the song goes, but Bert is here to show One Direction how it's done.
The lads from 1D have a string of their own hit songs, but they decided to go back to a real classic for their spot on Sesame Street. There's nothing like a good throwback — all the way back to preschool.
The boys were a little rusty with their letters, but Bert swooped in with a big finish. Harry Styles and Liam Payne may be pop superstars, but they're not afraid to share the spotlight with a talented Muppet.