Underage drinking is always polarizing, but after a recent incident, news outlets’ inaccurate reporting — and a 21st-century twist — exacerbated an already hot-button issue.

On Dec. 10, Montgomery County police gave citations to approximately 35 Walt Whitman High students who were caught drinking at a Bethesda house party. Then, last month, ABC 7 News (WJLA) reported that Whitman’s principal, using what he found on students’ Facebook pages, suspended at least three dozen students from extracurricular activities. The next day, WTOP news radio claimed, “Fourteen students at Walt Whitman High in Bethesda have been suspended from extracurricular activities after the principal discovered pictures on Facebook of them drinking at an off-campus party.” The Gazette and several Patch news sites’ coverage also included errors.

Message boards, forums and listservs — not to mention Facebook and Twitter — lit up with debates, nasty comments and overwhelmingly negative protests. Schools have “no jurisdiction over those kids if it didn’t happen on school property,” local viewers argued. Commenters maintained that a school’s job is to “educate,” not to parent; that schools shouldn’t “stick their noses where they don’t belong.” Many of the attacks targeted Whitman principal Alan Goodwin, accusing him of “abusing his power” and “stepping out of bounds.” His actions were “snoopy and neurotic,” sniped one poster. “Perhaps he has too much time on his hands, listening to ‘gossip’ and surfing ‘Facebook’?”

It’s probably safe to say that most principals do not have that kind of time. Would that they did. Regardless, here’s what really happened, according to Goodwin, who says he first learned about the party from Whitman’s athletic director after athletes confessed to coaches that they had received citations. Within hours, another student told Goodwin that news of the party was “all over Facebook.” Eventually, students, coaches and party attendees shared the names of 11 of the 35 students who had been cited.

Goodwin didn’t summon students to grill them about the names of the partygoers; he says he doesn’t encourage “kids snitching on other kids.” He did not surf Facebook to identify additional perpetrators. (Goodwin doesn’t even have a Facebook account.) Instead, he gave each of the 11 identified students a minor school-related punishment, which is Whitman policy, as stated in the school’s handbook and athletic participation contract. The five student athletes had to sit out their next two games, for instance, and the students who were not involved in extracurricular activities had to serve a few hours of community service.

So Goodwin did not, as ABC 7 reported, launch “a social media investigation.” But let’s say he did. Facebook isn’t a personal diary. It’s a public space, the 21st-century equivalent of a teen hangout like the 1950s roller rink or 1980s mall. If students are posting pictures or updates about illegal activities in a public domain, they can’t expect adults to ignore them. By now, anyone who uses the site should be well aware that if you want something to remain private, you certainly don’t post it on Facebook.

Social networking is also a continuation of the social part of the school day, and behaviors that occur online can spill over into school activities. For example, when Whitman administrators learn that Facebook posts have sparked taunting with a rival school before a big game, they sometimes hire extra security to monitor that game.

Even more to the point, in today’s landscape, parents frequently ask administrators to help fight cyberbullying that occurs on Facebook; this, too, has happened at Whitman this year. (In such cases, rather than go on Facebook themselves, administrators ask the bullied students to bring in printouts of the offending pages.) In effect, some parents are seeking a Facebook double standard: “Please protect my child from one type of negative behavior, but don’t concern yourself with another.”

Those parents are missing the real messages, which have been buried beneath a cloak of sensationalized misinformation: That communities should thank, not berate, any principal who goes out of his way to keep students safe. And that what happens on Facebook doesn’t stay on Facebook.

Alexandra Robbins is the author of “The Geeks Shall Inherit the Earth” and “The Overachievers,” which was based at Walt Whitman High School.