As impressive as the students of Marjory Stoneman Douglas High School have been in calling attention to the issue of gun violence — and as much as their upcoming protest, “March For Our Lives” in Washington is likely to draw considerable attention to their cause this Saturday — we can’t help but offer one cautionary word of advice to the hundreds of thousands of young people headed to D.C.: Make your case, share your feelings, but stick to the facts. As much as it might be tempting to embellish (and thereby emulate the behavior of the nation’s elected leaders), it’s better to double- or even triple-check your claims. In the “swamp” of national politics, it’s always best to occupy the high ground.

We don’t make this suggestion lightly. We make it because this edition of our “Alternative Fact of the Week” feature provides a perfect example of where the gun debate could go horribly wrong. In a posting that’s made considerable rounds this week on Facebook and other social media, there’s a photograph of the thousands of pairs of shoes that were placed on the lawn of the U.S. Capitol to honor those who have died in gun violence along with a photograph memorializing Americans who have died in combat. And it all carries the claim that 7,182 students have been shot to death in U.S. schools since 2012 compared to 6,915 U.S. troops killed in overseas combat since 2001.

It’s a powerful statement. A sickening thought. But it’s also completely wrong. And it surely doesn’t require more than a few minutes of search-engine time to realize it’s a gross exaggeration of the school shooting phenomenon.

First, there’s the relatively minor mistake with respect to the service deaths, which are currently listed by the U.S. Department of Defense as 6,929, not counting another 21 defense-employed civilians. Far worse is the conflation of gun deaths by minors with students killed in school shootings. They are not the same thing. The shoes placed in front of the Capitol were to symbolize young people killed in all kinds of shootings — in homes, in streets, in back alleys, even suicides — since Sandy Hook. School shootings represent just a small fraction of that group.

How many people have died in school shootings over the last six years? There’s no official total. But estimates by news organizations such as The New York Times peg the number at 138, including adults, or roughly 2 percent of the claim. Even by the most generous standards of Donald “biggest tax cut in history” Trump accounting, that’s way off the mark. In the parlance of D.C., this is a prime example of fake news.

Throw around numbers like that, kids, and here’s what happens next. You can watch your whole argument about gun violence, about the nation’s failure to protect your lives, about the idiocy of allowing powerful and deadly tools of war to be put into the hands of any Tom, Dick or Harry who isn’t even old enough to buy a beer be set aside as the right-wing trolls attack your erroneous accounting. This is what public debate in this country has been reduced to — the kind of bluster and bullying that your schools wouldn’t countenance on the playground but is standard operating procedure in the nation’s capital.

Who knows where such claims get planted on social media, whether it’s well-meaning supporters or Russian bots looking to sabotage our public squares, but you will have to do your homework, which we have no doubt you are fully capable of doing. If Douglas leaders can brush off the slings and arrows that have already been tossed their way (from the GOP candidate in Maine who called one of the student leaders a “skinhead lesbian” to the right-wingers who claimed they were “professional protesters”), they can surely keep to the straight-up truth because it’s bad enough without any additions or subtractions.

“We call BS” was the rallying cry from Parkland, Fla., one month ago. It captures exactly where the students are coming from — innocent, victimized, horrified but still believing their country can do better — with maybe just a bit of youthful passion mixed in. So don’t give others the chance to call BS on you.