Tyler James Williams on Janine Impersonation

SPOILER ALERT: This article contains major spoilers from the Season 4 finale of “Abbott Elementary,” which aired Wednesday on ABC and streams Thursday on Hulu.

While “Abbott Elementary’s” Janine (show creator and star Quinta Brunson) and Gregory (Tyler James Williams) are going strong in their relationship, that doesn’t mean that impersonating each other in one humorous sequence during the Season 4 finale came easily for the actors who play them.

The episode, titled “Please Touch Museum,” follows Abbott’s teachers and students on a field trip to the hands-on Philadelphia museum, which is “for babies,” according to the school’s sullen eighth graders. To cheer the preteens up, the museum guide suggests they write a play about their time at “Abbott” — one that roasts their teachers. To make matters funnier, the students cast their teachers to play one another.

“I found it difficult, actually, to do Janine because there’s not really much to pull from. She’s just kind of happy,” Williams told Variety on Tuesday at the show’s season finale event at the Academy Museum of Motion Pictures in Los Angeles. “We knew it was going to be one of those unhinged scenes, and we got a chance to just play around with each other.”

When Brunson told the cast about the premise, Chris Perfetti immediately thought, “Please don’t let it be Barbara,” hoping he wouldn’t have to mimic Sheryl Lee Ralph’s bible-quoting kindergarten teacher. “And sure enough, here we are,” Perfetti cracked. (Likewise, Ralph impersonated Lisa Ann Walter’s tough-talking teacher, Melissa, while Walter imitated Perfetti’s awkwardly enthusiastic character, Jacob; William Stanford Davis’ eccentric janitor, Mr. Johnson, played himself.)

“Like everything Quinta does, it was funny, but it has such an underlying heart to it,” Perfetti added. “I’m kind of surprised that we hadn’t done that yet.”

Brunson recalled when the idea was pitched in the writer’s room. “We were in that place where we had written, ‘What are we gonna have the eighth graders do to have fun?’ We really didn’t know when we started,” Brunson said. “It was way funnier than I expected it to be when I actually saw it.”

So much has happened at “Abbott” over the course of 22 episodes. While looking back on some of the season’s major themes, Walter said she felt “gratified” at getting to be part of the labor dispute storyline since she’s served on the SAG-AFTRA negotiation committee.

“I think on purpose they were like, ‘Make Melissa be the mounting voice of the union!’ And I’m like, ‘Great, put a big target on my back!’ But I love it,” Walter said. “I love that we were pro-union, and Philly is such a union town.”

Season 4 was a whirlwind for Janelle James’ Ava, ranging from getting fired as principal (then reinstated) to slowly falling for the school district’s IT tech O’Shon (Matthew Law) — and the character’s growth continues in the finale.

“It was a catalyst to have Ava reveal even more about herself and soften up a little bit,” James said about her character catching feelings. “But what I really like about it is that although she’s entering her soft era, she hasn’t changed her core personality. That’s what’s so good about the writing on the show — nobody just does a 180.”

So what’s next for the teachers of “Abbott”? Even though the hit ABC comedy received a full order for a fifth season months ago, Perfetti says that Brunson and the writers won’t drop hints to the cast until they need to know what’s happening, but he has one wish for the upcoming episodes.

“I feel like we’re kind of testing the limits of what Jacob’s physical comedy contribution to the show is, so that’s my only hope for next year,” Perfetti said. “But I have every faith in Quinta and our writers who, in many ways, know us better than we know ourselves.”