Viewers looking forward to watching "Young Sheldon" when it debuts on CBS this fall shouldn't expect a mini-"big bang theory." The network promises that the two shows will be very different. For one thing, "Young Sheldon" is more of a single-camera, laugh track-free show, whereas "Big Bang Theory" is a multi-camera series. CBS Senior Vice President Kelly Kahl also said that the show's tone could be, in fact, more likened to "The Wonder Years" or "Doogie Howser."

Picking Iain Armitage

"Young Sheldon" follows the 9-year-old version of "Big Bang Theory's" lead character, Sheldon Cooper. He's starting out high school as a genius student in Texas in the year 1989.

Playing the lead in "Young Sheldon" is child star Iain Armitage, who is only 8-years-old in real life. Viewers may recognize him on the critically-acclaimed "Big Little Lies" show on HBO where he played Shailene's Woodley's son, Ziggy. The boy's character was wrongly accused of bullying a classmate in the drama series.

Executive producer Jim Parsons, who plays the adult Sheldon in the original show, said Armitage really stood out during his audition. The actor revealed they saw plenty of tapes of young actors but Armitage "popped immediately," as per Entertainment Tonight.

Jim Parsons has since been coaching Armitage on how the younger version of his character should behave, especially after playing him for 10 years. Parsons said the budding young star is listening well and is a better actor than he was at this age.

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More 'Young Sheldon' details

Aside from Armitage, the show also stars Zoe Perry as mom Mary, Lance Barber as dad George, Montana Jordan as brother George Jr., and Raegan Revord as his twin sister Missy. Perry is actually the real-life daughter of Laurie Metcalf, who plays Sheldon's mom in the original series.

Working alongside Jim Parsons as the show's executive producer is Todd Spiewak, his real-life husband. "Big Bang Theory" bigwigs Chuck Lorre and Steve Molaro co-created the show and have also enlisted Jon Favreau as executive producer. Incidentally, Favreau directed the pilot episode for "Young Sheldon."

CBS plans to debut the show on Monday, Sept. 25. Then, it will fall into the Thursday time schedule by November. Meanwhile, "Big Bang Theory" will return for Season 11 in the fall. The previous season ended with a cliffhanger where Sheldon proposed marriage to his long-time girlfriend Amy Farrah Fowler (Mayim Bialik).