"Miranda Cosgrove, Jerry Trainor, Jennette McCurdy, Nathan Kress, Taran Killam and Michelle Obama on “iCarly.” (Lisa Rose/NICKELODEON)

If you happened to miss Michelle Obama’s relatively historic appearance on “iCarly” Monday night — which is definitely possible if you are not a tween — here’s all you need to know:

* Back story: “iCarly,” the kid-friendly sitcom on Nickelodeon, stars Miranda Cosgrove as Carly, who has her own wildly popular Web show with wacky sidekicks Sam (Jennette McCurdy) and Freddie (Nathan Kress). They live in that magical TV world where parents are never around; but in Carly’s case, that’s because her dad is serving overseas in the military. Carly’s dad’s birthday is coming up, and when he can’t make it back home to visit, the tech-savvy friends tap into the military Internet system and set up a special birthday celebration via web cam. This gets the attention of someone high up in the government, which means...

* Michelle Obama appears! She arrives on screen 24 minutes into the half-hour show, after plenty of time for Carly and friends to worry that they are going to be arrested for using high-tech methods for the birthday web show. But, no worries — the first lady just wants to say that she admires Carly’s devotion to her military father.

“I was really touched with how much you love and care about your dad while he’s away serving our country,” Obama says, and then turning to the sidekicks: “As important as it is for Carly to support what her dad is doing, it’s just as important that she has good friends like the two of you to understand her situation and support her too.” Carly and pals are thrilled, and invite the first lady to appear on an episode of their web show.

* Robots and random dancing: Last year, Michelle Obama has made the rounds on TV — Winfrey’s Oprah’s former syndicated talk show, “The Gayle King Show,” “Sesame Street” — to talk about her campaign to provide support for military families. What made this appearance different, besides being a scripted series? This time, Michelle Obama had deliver several one-liners (including one about building a robot); joke about canceling on a governor to hang out with some kids (”Let the governor wait — come on, let’s go do ‘iCarly!’”); and, as is an “iCarly” tradition, participate in some “random dancing.”

Here’s video of said random dancing: