During the season premiere of the animated series “Arthur” on Monday, Arthur, Francine, Buster and Muffy spend most of their time trying to play matchmaker for their third-grade teacher, Mr. Ratburn.

In the end, Mr. Ratburn has his own plans. He ties the knot with Patrick, a local chocolatier, at a wedding attended by the students.

“Mr. Ratburn is married; I still can’t believe it,” Arthur says.

“Yup, it’s a brand-new world,” Francine responds.

The episode, titled “Mr. Ratburn and the Special Someone,” was the latest moment in daytime television to include a more diverse set of characters as it kicked off the show’s 22nd season. The series, which airs on PBS Kids and debuted in 1996, follows the adventures of Arthur, his classmates and his family.

“PBS Kids programs are designed to reflect the diversity of communities across the nation,” Maria Vera Whelan, senior director of marketing, communications and social media for children’s media and education at PBS, said in a statement. “We believe it is important to represent the wide array of adults in the lives of children who look to PBS Kids every day.”

In the episode, the students start to play matchmaker when they suspect that Mr. Ratburn might be marrying Patty, a woman they think is ill-suited for him. (She’s actually his sister.)

They try to set him up with a librarian, but it doesn’t work out. On the day of the wedding, Mr. Ratburn walks down the aisle arm in arm with Patrick, his partner. They smile at each other, and Patrick winks at Arthur in the crowd. Afterward, the students eat cake (Mr. Ratburn’s favorite), which was shown earlier in the episode with two toppers that resemble Mr. Ratburn and Patrick.

“Arthur” isn’t the only animated children’s show to recently feature same-sex weddings or relationships. Last summer the Cartoon Network series “Steven Universe” depicted a same-sex wedding in which the main character, Steven, officiated the nuptials of two female characters, Ruby and Sapphire. Another Cartoon Network series, “Adventure Time,” established a same-sex relationship when two main characters, Princess Bubblegum and Marceline the Vampire Queen, kissed.

“Sesame Street,” a PBS mainstay, has also tried to become inclusive. In 2017, the show introduced Julia, a female muppet who has autism. In September, the internet exploded over the possibility that Bert and Ernie might be gay partners. In December, the show introduced Lily, a muppet who is homeless and living in shelters and on friend’s couches.

The 2018-19 report “Where We Are on TV,” released by GLAAD, an organization that tracks representation of lesbian, gay, bisexual and transgender people in the media, noted some recent strides. The report found that “8.8% of broadcast scripted series regulars are LGBTQ characters,” a record high. Of the 857 series regular characters counted on 111 prime-time scripted shows across a variety of networks, 75 identified as LGBTQ, an increase from 58 in 2017.

“I think it is really important that LGBTQ people are having families in historic numbers and that we are seeing our family in media and reflected back to us, especially our children,” Sarah Kate Ellis, president of GLAAD, said in an interview today. Last year GLAAD added a category for children and family programming to its annual media awards because there was finally enough content to consider, she said.

“You know at a very young age if you are trans and gay or bisexual and lesbian,” Ellis said. “To be able to see yourself reflected is critical.”

Ellis said the openness that millennials — many who grew up watching “Arthur” — have about their lives and themselves have contributed to the increase in inclusivity across media platforms.

“I think that they are now in positions of power to create content, and they are reflecting the world as they know it,” Ellis said. “That is positive, and I think it is going to have a huge impact on the next generation of LGBTQ people.”

Some on social media said they were not nearly as surprised about Ratburn’s same-sex marriage as they were that “Arthur” was still airing new episodes.

“Season 22?! I didn’t know they were still making episodes of Arthur,” one user wrote on Twitter. “I used to watch it everyday as a kid. Also congrats to Mr. Ratburn and his love on their marriage,” one user wrote on Twitter.

It might not be a brand-new world for millennials after all.

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