Last Monday, twenty-one public-school students burst through the door of a building at Thirty-ninth Street and Lancaster Avenue, in West Philadelphia, for a session of Fake News Finders, an after-school workshop run by the nonprofit group Mighty Writers. An eight-year-old named Thomas parked his scooter opposite a framed photograph of Barack Obama beneath a “Black Lives Matter” banner. A ten-year-old named Musa carried his violin sheet music. James, eleven, had a backpack filled with snacks. All but three of the students were boys. Most found seats at a conference table.

“How many people know what fake news is?” the instructor, Annette John-Hall, asked. She is a former Philadelphia Inquirer columnist who now reports for public radio.

“News that is fake,” a student said.

“A made-up story,” said another.

John-Hall, a tall woman, who was dressed in a pink skirt, a navy sweater, and ankle boots, asked, “What’s the danger when you talk to other people about something that’s not true?”

“You’ll either end up in a war or a riot,” one boy said. “Something really bad will happen.”

At the back of the room sat Tim Whitaker, the former editor of Philadelphia Weekly. He founded Mighty Writers, in 2009, because the city had some of the highest rates of illiteracy and poverty in the country. Whitaker believes that in order to write clearly students must think clearly.

“We have a new President,” John-Hall said. “Who knows his name?”

A chorus: “Donald Trump.”

“Wait, wait, wait,” a teen-ager in a hoodie said. “Donald J. Trump.”

John-Hall said, “When you think about our new President, give me a one-word descriptor.”

“Evil.” “Dumb.” “Racist.” “Sexist.” “Disrespectful.”

John-Hall said, “There are facts to back up every single word you just used.”

She cued up a CNN video—“First 100 Days: Price of Protecting the First Family.” The students watched as the moderator, Don Lemon, interviewed guests about Mar-a-Lago and golfing and business conflicts.

“Paris, what do you think?” Lemon asked Paris Dennard, President George W. Bush’s director of black outreach. Dennard said, “I think this is fake news.” Lemon, clearly irritated, cut the interview short.

John-Hall explained to the class, “ ‘Fake news’ has been redefined, for a lot of people, as news that they don’t agree with.” But she also wanted the students to be alert to news reports that were simply fiction. The class discussed how to compare suspect material, like that produced by Infowars, with the journalism of credible news outlets. Khalia Robinson, who is Mighty Writers’ program director, offered an example: TMZ (real) and TMZWorldNews (parody).

Musa asked her, “Why do you watch TMZ?”

“I don’t, but I do follow the links so I’ll know the difference,” Robinson said.

“My mom watches TMZ,” Musa said. “I tell her it’s inappropriate.”

They moved on to how fake news spreads. John-Hall asked the students which social-media platforms they used.

“Instagram.” “Facebook.” “Google Plus.” “Snapchat.”

“Google Plus?” someone said.

John-Hall said, “Can somebody tell me the danger in sharing something that isn’t true on social media?”

More students mentioned war, and John-Hall agreed that President Trump’s behavior had “international ramifications.” She said, “Our own President doesn’t know how to tell the truth.”

“Even a kindergartner can tell the truth,” a boy said.

James, who was halfway through a bag of Cheetos, asked what “international ramifications” meant.

Next, John-Hall asked for clues to spot fake news. “Let’s say you’re reading something about Beyoncé,” she said.

“Don’t use that as an example,” another boy said, groaning.

“O.K., let’s say you’re reading something about Kevin Durant—”

“Even worse.”

“Kevin Hart!” a small voice said.

“O.K., Kevin Hart,” John-Hall repeated. “Let’s say you’re reading something that says Kevin Hart played in a celebrity basketball game, and he blocked Kevin Durant’s shot.” Everyone laughed. “Why would your common sense tell you that’s not true?”

“Kevin Hart’s too short to be blocking some shots!”

“That’s right!” John-Hall said. “You know Kevin Hart is no taller than Musa!”

After they’d discussed telltale signs of fake news such as mismatched fonts and bad grammar, John-Hall asked, “What about quotes? Like, if Kevin Durant says, ‘Man, I can’t stand Steph Curry and I can’t stand Draymond Green.’ ”

Julius, nine, raised his hand: “I don’t think anybody likes Draymond Green.” ♦