'Glee' 100th Episode, By The Numbers

See, education can be fun, just like Mr. Schue said!

This week's episode of "Glee" is all about the numbers: It's the series' 100th episode, a half-dozen cast members and guest stars who aren't gracing the (surprisingly well-kept) plastic chairs of the McKinley High School, and New Directions is in trouble over the number of dollars of school funding (zero) it has left. The episode even takes its name, "100," from the centurial number.

In fact, if one were to that narrow slice of Venn diagram overlap between "hardcore 'Glee' fan" and "someone who needs to teach a small child to count," this episode would be a great tool.

1. New character introduced named "Biff." Wassup, Chace Crawford.

2. Pairs of over-the-knee socks in the Glee clubroom. (Rachel and Brittany, natch.)

3. Minutes into the episode it took to hear Mr. Schue say "gangsta."

For the sake of brevity, let's jump forward a bit.

2 million. Number of dollars Mr. Schuester has spent on the Glee Club's sets to perform for "literally just you" in recent months, according to Principal Sylvester's painstaking accounting.

In Tuesday (March 18) night's episode, the first part of a nostalgia-filled two-parter in honor of the show's milestone, tears were shed, guest stars resurrected and plotlines stalled in favor of what may be the most meta episode of "Glee" ever.

Mr. Schue, in recognition of the demise of New Directions, calls the troops home to Lima to cry a lot while looking at a plaque of Finn and to "reinvent in some way" old Glee Club songs for their final assignment. (Weirdly, none of the graduated members of the club pull a "you're not the boss of me" and storm out. Actually, only Gwyneth Paltrow realized the absurdity of Schue's request and dared defy him.)

Here are the highlights of last night's episode.

April Rhodes - "Raise Your Glass"

April (Kristen Chenoweth) and her adorable pixie cut busted in, called everyone virgins and then grabbed Blaine's face while screaming "HOOOOOONK." This is not a drill. The momentum of this number glided us into the rest of the episode before anyone could say "pardon me?"

Quinn, Brittany and Santana - "Toxic"

Dubbing themselves the "Unholy Trinity," the trio of former cheerleaders reunite for a Britney number. (Never forget Brittany S. Pierce's unfortunate name.) But, hey, real talk: the Chicago homage-meets schoolgirl whatever look is cool and everything, but like...were Quinn, Brittany and Santana instructed to bring their Cheerios uniforms with them for the real-world version of the performance? Just checking, because we'd love to see that email.

Kurt, Rachel and Mercedes - "Defying Gravity"

"Apparently the only song you can sing in a diva-off is 'Defying Gravity,'" Mr. Schue whines after Rachel and Mercedes argue over seating arrangements and who's the baddest b---- in the McKinley alum hall of fame. Poor Kurt, who also sings the song, is fully ignored in the ensuing vote, where Rachel and Mercedes are dubbed to be equally divatastic.

Santana - "Valerie"

After Math Genius Brittany admits that she misses high school, when "all I wanted to do was scissor you and talk to my cat," Santana decides it's time to dance.

Puck - "Keep Holding On"

Puck makes everyone walk to the auditorium, apparently while inaudibly muttering to himself, "oh, she's so totally gonna cry" and pulls out this Season One classic, originally directed at Quinn to let her know that everyone's still super into her even though she's going to be a teen mom. This time, Puck wants it to mean that he's still super into her even though she's dating a guy named Biff and totally denying that she was a teen mom. There's always a sticking point, isn't there? Cue waterworks.

Gwyneth Paltrow - "Happy"

Because it's never not a good time for some GOOP lovin', we're gifted with the presence of Gwyneth Paltrow herself. (Her character has a name, and it's Holly, but let's be real and call a Gwynnie a Gwynnie. We're Shakespeare, and we're so in love.) She delivers the all-time classic line of, "April, thank you for buttering the floor for me, you know I love to make an entrance" before leading the club in a lil jam sesh.

See you next Tuesday, which we assume will be a real emotional journey for the characters. (Get it, because they held off singing "Don't Stop Believin'" for an entire episode? Journey. Yeah.)