BURBANK, Calif. – Sitting on a paint-chipped porch chair overlooking the backyard of his fake childhood home, "Young Sheldon" star Iain Armitage takes a moment to savor the green grass.

Actually, there are more sizable pockets of dirt than grass outside the Cooper family's humble East Texas abode, created on a Warner Brothers soundstage. Still, it's a home for Armitage, 15, who was just 8 in 2017, when he started playing the pint-sized version of Jim Parsons' adult genius Sheldon Cooper in the prequel spinoff of CBS hit "The Big Bang Theory."

"I used to fit in those swings," says Armitage, eyeing the faded metal backyard swing set. "Now I'm too large. I tried it again two hours ago. I didn't tip it over, so I'm counting that as a victory. But I rocked the swing set, so it's a little unsafe for me now."

But childhood – and TV shows – inevitably come to an end. Armitage soaks it all in while taking a break from shooting some of the final scenes for the May 16 hour-long series finale (8 EDT/PDT). Just as the adult Sheldon reminisced on "Big Bang Theory," the 14-year-old Sheldon will finally leave East Texas for the California Institute of Technology.

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Both franchise lore and Armitage's age provided a cap for the prequel series and the reason to end it after seven seasons, says "Big Bang" and "Sheldon" co-creator and executive producer Chuck Lorre. 

"In the 'Big Bang' universe, Sheldon goes to Caltech at 14. Even if we ignored that, the show is called 'Young Sheldon,' and that's not true anymore," says Lorre. "We got to watch this guy grow up, and it was wonderful. It's heartbreaking to end, even though it was the right story decision. It just felt like the right time. But it didn't make it any less emotional."

Armitage, a trooper ever since CBS announced the end was nigh last November, is not prone to tears, even on the second-to-last day of shooting.

"I feel weirdly calm," he says. "I'm definitely going to miss being here. But I feel so lucky and grateful at the same time. So it all swirls together in my mind and they cancel each other out. I'm definitely sad. But I think it's hit a lot of other people harder than it's hit me."

That's for sure. During one break, Annie Potts, who plays Sheldon's Meemaw, wanders through the ranch-style Cooper house with Raegan Revord, who plays Missy Cooper, admiring family wall photos as if for the last time. Holly Revord, Raegan's mother, doesn't hide her tears or the balled-up Kleenex in her hand, watching the monitor as her daughter shoots scenes in Sheldon's packed-up bedroom. Matt Hobby, who finished shooting his final scenes as Pastor Jeff earlier in the week, has solemnly returned to show his support for the cast.

Nearby in the writers' room, executive producers Steven Molaro and Steve Holland, both veterans of "Big Bang Theory," which ended its celebrated 12-season run in 2019, have a tissue box nearby.

"We've both been through this on 'Big Bang' as well. So many 'lasts,' the last day for this character and so on. Each day I think, maybe I'll get less emotional. Then I get emotional all over again," says Molaro. "All the writers were crying in the writers' room coming to the end, writing all the things happening on the show."

"It's been a ride," says Holland. "It's been really exciting to see these scenes play out. There have been some emotionally difficult scenes. These last couple of episodes the tissue box came in handy."

Notably difficult was the May 9 episode, which featured the death of George Cooper Sr. (Lance Barber). The flawed but lovable father's offscreen heart attack death was preordained, a pivotal event older Sheldon discussed in "Big Bang Theory." Obviously, Sheldon and his family were stunned by the news as the episode ended.

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The series finale starts with the Cooper family's shock and grief over the loss and then strives for the pitch-perfect upbeat series ending that takes place 27 days after George's funeral. Jim Parsons, who narrates "Young Sheldon," reprises his character for the finale, along with Mayim Bialik, now Sheldon's wife and mother of their two children.

After the funeral in the finale's first half, Molaro says, "We go to a more uplifting area and give the characters a chance to move on. We still have the ultimate moment where Sheldon goes to Caltech and starts his new life. So there was a way for us to pull out of the nosedive of George's death and leave on a brighter note."

Many scenes Armitage shoots on this April day involve meticulously boxing up his prized train collection for college, a callback to the "Young Sheldon" pilot.

"The first scenes of our show ever were of Sheldon's trains. We opened the series on my toy – sorry, my historical facsimile trains – going around the track," says Armitage. "And now, seven seasons later, I'm packing my trains. It's a great symbol."

The "Big Bang" franchise continues this fall with another prequel spinoff following older brother Georgie (Montana Jordan) and his wife (Emily Osment) in "Georgie & Mandy's First Marriage," airing in the same time slot. But it's the end of the line for "Young Sheldon." While sticking the series landing is tough, the team is cautiously confident they have done right by everyone with the finale.

"We've thought for a long time about how to end the show. There's a lot of pressure there," says Molaro. "We care about these characters as if they're real people. And we wanted it to feel satisfying and do right by them as best we could."