Glee fans are likely well aware at this point, but Gwyneth Paltrow guest stars on Tuesday's episode as Holly Holiday. Yes, that's the name of a teacher, not a porn star, something Terri asks the character about.

This substitute takes over New Directions when Will comes down with a sickness, as previewed in this video. Spoilers have already revealed that Paltrow will sing a pair of tunes on the episode:

1. A mash-up of "Singing in the Rain/Umbrella."
2. A take-off on Cee Lo's "F-ck You," titled "Forget You."

In the following video, we've provided fans with a preview of these and other singles covered on "The Substitute." Watch, listen and enjoy.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.