The kid cast of the PBS series “Odd Squad” is gearing up for its usual challenge, teaching kids about math and science. While the four new members of the team tape scenes in New York’s Central Park, however, a bigger threat looms.

Viewers of “Odd Squad” will not be all that familiar with Valentina Herrera, Jayce Alexander, Alyssa Hidalgo and Gavin MacIver-Wright when they take to the PBS Kids schedule sometime in 2020 for the third cycle of this popular kids’ program. Producers are betting fans of the program and others who have yet to sample it will embrace them quickly. A cast shake-up is not the norm for most series, but for “Odd Squad” it has fast become de rigueur.

Across kids’ TV, most favorites rarely change. Curious George looks almost the same now as he did when he debuted in 2006. The same is true for Nickelodeon’s SpongeBob SquarePants. Just as its young agents solve problems using unorthodox methods, so too do the show’s producers, who rely on the series’ live-action feel to keep a rising generation of TV viewers interested in what’s happening.

“There’s entirely too much of it,” says J.J. Johnson, founding partner of Sinking Ship Entertainment, which produces “Odd Squad” along with Fred Rogers Productions, speaking of animated series for children. “We are trying to get kids excited about the real world.” He adds: “I just think kids connect to kids they see who are like them. It’s important for kids to see themselves represented on screen. I think this show does that.”

Since its launch in 2014, “Odd Squad” has captured young eyeballs through an interesting conceit that casts kids as part of a vast network of secret agents who aim to solve all kinds of mysterious phenomena using logic and reasoning. The producers lace the live action with special effects and funny, original songs that often spark viral pass-along.

The challenge is the one that looms for any executive behind the operations of a live-action kids’ favorite. Within the space of just a few seasons, the actors get too old for the role. Little wonder that Disney Channel’s “Liv & Maddie” or Nickelodeon’s “iCarly” last just four to six seasons. “Odd Squad” must also contend with the fact that PBS tends to broadcast a small handful of episodes at a time, parceling out originals just a few times a year.

The “Odd Squad” cast has been through two iterations, and will now debut a third. In this go-round, the show will focus on just four agents, who function as part of a mobile squad, and will travel to places ranging from New York to Australia. Viewers who have followed the show in the past will notice the series’ evolution as soon as the squad members step into their new van, says Mark De Angelis, the program’s co-executive producer and writer. “They step into it for the first time and they say, ‘How is this thing way bigger on the inside than it is on the outside?’” he explains. The show “still has the same magic,” he adds. “It’s a little more intimate.”

Not necessarily for the four new cast members, who are navigating some of the series unique quirks. Jayce Alexander, 11 years old, says one of his most challenging scenes so far required him to rattle off a bunch of fractions. “I was like, ‘three-fourths, two-fourths, five…one-fourth, two-fo….I quit.” Gavin MacIver-Wright, also 11, had to muddle through tongue-twisters. Alyssa Hidalgo’s character is several centuries old and wears an ornate hairpiece she says takes 20 minutes to get on her head. Valentina Herrera plays Opal, a mission-driven agent. ‘We have to keep going,” she says, “She’s really the ‘get-going’ of the group.”

Gone are Anna Cathcart, the former Agent Olympia, and Isaac Kragten, who played Agent Otis. Longtime viewers will be encouraged to learn that Millie Davis, who has played leader Ms. O since the series started, remains on hand as a now-legendary guiding light known as “The Big O” (Johnson acknowledges that producers are working harder than ever to keep the series in characters with “O” names).

“Changes are never easy for kids,” notes Suzanne Masri, director of marketing and communications for Fred Rogers Productions, but producers know a certain segment of the audience grows out of the show year by year, and are working well ahead of the launch of the next cycle to make certain audiences are aware of the new lineup and storyline. “We are pretty confident this new cast will find a new place in viewers’ hearts, like the other casts have,” she says.

And there are other avenues to consider as well. Producers already launched an accompanying series of streaming-video snippets on “Odd Tube.” Now they plan to launch an audio component, an “OddCast.”

The hope is the changing casts will give future fans more to watch. “Kids will find the original season and the sequel cast in the second season,” says Johnson. “The ‘Odd Squad’ world is massive, and it just keeps folding out.”