Ricky Martin, Heather Morris and Harry Shum Jr., show off their chair dancing skills on this week’s “Glee.” (Adam Rose/Fox)

Ricky Martin made his guest appearance on “Glee” last night, in what was clearly a watershed TV moment. To my knowledge, this marked the first time that a Latino actor has ever appeared on prime-time television in the role of an Ohio-based adult ed Spanish instructor and former teeth model who, secretly, possesses the singing and dancing skills of a former member of Menudo.

As expected, Martin brought his charm, energy and swiveling hips to the proceedings. And also, sadly, as expected, “Glee” brought more narrative developments that didn’t make sense. Among the many questions raised in the episode, “The Spanish Teacher,” the most Latin-flavored episode since Gwyneth Paltrow showed up last season and encouraged the kids to “go get some tacos”:

—How is it possible that Will Schuester (Matthew Morrison) has been teaching Spanish for so long and just now, midway through this episode, learned the definition of “muy”? Could he not have paid for a Spanish-to-English dictionary or app of some sort?

— How come Mercedes (Amber Riley) went to see Miss Pillsbury to sort out her conflicted feelings for Sam and Shane, but brought Sam with her? In what way did that make sense?

—Why, exactly, did Emma Pillsbury (Jayma Mays) earn a much-coveted tenure position as a history teacher when she’s been working at McKinley as a guidance counselor and handing out absolutely horrifying self-made pamphlets? (“Taint Misbehavin’”? Really?) In a non-related matter, I’d also like to know where Emma got the dresses she wore in this episode because those were super-cute.

—Wouldn’t Sue Sylvester (Jane Lynch), who suddenly wants to be a mother, have been fired immediately for asking the male members of glee club to donate sperm to her cause, then requesting that Will deposit some “baby gravy” in her office?

— Why am I still recapping this show by the musical numbers when another, slightly more logical musical show called “Smash” is now airing on NBC?

Ah, that last question I know the answer to: because this blogger liked to live la vida loca. So enough yapping. Vamos a la música!

“La Cucuracha” — Mr. Schuester, Puck, Finn and Artie

“I’m ashamed,” Will thought to himself as a he danced around like a culturally clueless Speedy Gonzalez imitator in front of his Spanish students in this mercifully brief opening number.

Ashamed — yeah, that’s about right. Grade: D (Can’t give it lower since this was intentionally awful, but good grief — Mr. Schuester always seemed a bit more sensitive than this.)

“Sexy and I Know It” — David Martinez (Ricky Martin) and New Directions

In case you didn’t hear enough of this LMFAO song during Madonna’s Super Bowl performance, Martin did it again here — and partially in Spanish!

Although he did not attempt any Madonna-style handstands, Martin did what he does very well: dance and sing with high intensity ... or, to use a word oft-repeated last night, duende. And the kids responded, matching every goofy facial expression with another, even goofier facial expression. The chair dancing also was impressive. I just wish they had chosen a better song for Martin’s splashy “Glee” debut. Grade: B-

“Don’t Wanna Lose You” — Mercedes (Amber Riley)

In keeping with the theme of doing music by Latino artists and/or in Spanish, Mercedes sang this Gloria Estefan ballad, with a mix of English and Spanish. Riley was reliably on-pitch, and the number was fine, just not particularly interesting. Grade: C.

“Bamboleo/Hero” — The male New Directions members

(Adam Rose/Fox)

A mash-up of Gypsy Kings and Enrique Iglesias was a fun choice. And it would have been a fun number if we hadn’t been so focused on the constant camera shots of those Mexican hipster boots, which, as worn by the Gleeks, looked like the results of a failed scientific experiment involving the shoes worn by Santa’s elves.

“Muy serious footwork,” noted Mr. Schuester, demonstrating his firm understanding of the word muy. Try muy distracting. Grade: C+

“La Isla Bonita” — David and Santana (Naya Rivera)

All right, now we’re getting somewhere. It didn’t make sense that this onstage performance by Mr. Martinez and Santana had such high production values, including a pseudo-laser light show. But inexplicably high production values are a “Glee” staple, and I was willing to overlook them because these two looked great together, meringued beautifully and sounded smooth. Grade: B+.

“A Little Less Conversation” — Mr. Schuester

(Adam Rose/FOX)

Matthew Morrison managed to give his all to this Spanish-infused Elvis Presley cover, even though he looked pretty ridiculous in that matador outfit and it made no sense that he was suddenly backed up by a Herb Alerpt and the Tijuana Brass cover band.

I also give bonus points to this number because it was followed by the one “Glee” line last night that made me laugh out loud, courtesy of Santana: “Why don’t you just dress up as the Taco Bell chihuahua and bark the theme song from ‘Dora the Explorer’?”

A joke, maybe. But given how silly this episode was, that also sounds like a potential concept for Ricky Martin’s inevitable return to “Glee.” Grade: B.