The preschool teacher panned her iPhone camera over two bowls of water, set side-by-side and dusted with thick piles of pepper.

As her students watched on Zoom, Jennifer Cross coughed into the first bowl, sending black flakes flying. Then she stretched an orange mask, patterned with swirls, over her mouth and coughed into the second.

No movement, she pointed out, adding that the pepper flakes are just like germs.

“Which is why it’s important,” Cross told the children, “to wear a mask!”

Cross’s co-teacher, Casey Zebell, chimed in then to remind the dozen 3- and 4-year-olds, one of whom was jogging back and forth across his sofa, that it was still Ms. Cross underneath that mask, even if they could no longer see her face. The lesson, held last month, was the teachers’ second devoted to mask-wearing — explaining it, justifying it, making it seem less outlandish — since the novel coronavirus forced the closure of all Virginia schools, including the Nysmith School for the Gifted, a Herndon private school that offers prekindergarten through eighth grade.

“It was the elephant in the room,” Cross said later. “I don’t want them to see masks as a negative.”

Since April, federal health officials have recommended that all Americans over the age of 2 wear masks in public, although the government has provided little guidance on how to achieve this among the finicky under-10 crowd. As summer begins and segments of society start to reopen, teachers and parents are working to persuade kids to keep cloth coverings behind their ears, over their mouths and across their tiny nostrils.

Educators are getting creative, pasting pictures of masked superheroes into PowerPoints, asking children to sketch fantasy face coverings at home, donning masks and dancing deliriously to prove that masks cannot stop fun. Parents are ordering custom coverings featuring their children’s favorite characters, tying masks behind teddy bear ears and trying to mix indoor mask-wearing into daily household routines, meant to make the frightening familiar.

It is not easy. Kids call masks uncomfortable and unnerving, whether planted on their own faces or someone else’s.

“It feels,” said Nysmith student Aiden Yan, 4, “like I cannot breathe.”

The challenge will become more pressing in the fall, if bricks-and-mortar schooling resumes. Administrators will probably ask teachers and students to cover their faces, especially after the Centers for Disease Control and Prevention recommended in May that all educators wear cloth masks, should campuses reopen.

“You can’t just flip a switch,” said Bob Farrace, public affairs director of the National Association of Secondary School Principals. “Schools need to start well in advance by getting kids used to masks in a comfortable, secure environment.”

In Fairfax County Public Schools, teacher Laura Balzotti asked her brother-in-law, a scientist, to guest-star in a video for her pre-kindergarteners. She introduced him as someone who deals with “things that can be proven to be true,” and he explained that masks prevent germs from getting inside children’s bodies.

Balzotti backed him up by splattering a paper towel with slimy green liquid, demonstrating what happens if you sneeze sans mask.

“I think we underestimate kids’ capacity for understanding,” Balzotti said in an interview. “If we just take the time to break down ideas for them, especially with visuals, they get it.”

In Arlington, the Chiarodo family broached the subject with their three children, all under 12, by playing a game: What can we use around the house to cover our faces? Suggestions progressed from old T-shirts to socks to underwear. It ended when Mom covered her face with a diaper.

Now, the family keeps a covey of cloth masks in a basket near the front door. They are required for trips outdoors and suggested as props for indoor play. Anthony, 9, is the only Chiarodo who has taken up the offer, occasionally ambling to the door to don his favorite gray mask.

“I don’t really know why,” Anthony said. “It doesn’t feel much different with it on.”

That is not the case for the Thierry family, a few streets over. Melissa Thierry has tried modeling best behavior, hoping her children will adopt masks if they see Mommy and Daddy wearing some.

Joseph, 4, hates the way the cloth makes it hard to talk or ask questions. Things are even harder for Julia, 5, who has Down syndrome. Her ears and nose are smaller than average, meaning masks fit poorly, and she struggles to understand why she needs to wear one.

Still, Melissa keeps working, taking them on daily practice walks, asking them to keep their masks on for 10 and 15 minutes at a time. She is making progress. On a recent morning walk, Joseph turned to see his sister trying to jerk off her mask.

“Juuuulie,” he said, running to her. “Over your nose! Over your nose!”

At Nysmith, Zebell and Cross decided to offer their first lesson on mask-wearing late last month. Cross, who has a 5-year-old and a 2-year-old, had noticed her own children giving double takes when they passed people on the sidewalk wearing them.

“I wanted to show that the things that make you you are still there, in a mask,” Cross said. “Even if you can’t see your nose or your mouth.”

The two teachers cobbled together a lesson from social media posts and the tactics Cross found effective with her family (“mostly honesty,” she said).

After the pepper test, the teachers flicked through a slide show filled with familiar figures — Elsa from “Frozen,” SpongeBob, Minnie Mouse —­ shown first without a mask, then wearing one. They also asked the children to identify various Nysmith employees, who had sent in masked selfies.

“Masks can sometimes make your face itchy and hot,” Zebell said, but “superheroes wear masks every day!”

She told the children face coverings made them superheroes, too, and asked if anyone could tell her why it is important to keep masks on outdoors. Avaline Kellogg, 4, tried to yank away the lilac mask her parents had asked her to wear. Her mother bent and pulled it back above her nose.

Aiden shot his hand into the air.

“Because-of-the-coronavirus,” he said in a rehearsed rush. “You-don’t-want-it-to-infect-you.”

Aiden still does not like his mask, which is big and blue and nameless (although he is considering options including “a fish name” and the French word for blue). But wearing it, he said, makes him feel safe.

“You gotta wear masks,” he said, “to protect you.”