TV’s most popular show, "Big Bang Theory" is getting a prequel! "Young Sheldon" is about Sheldon Cooper when he was a nine-year-old high school student. Jim Parsons plays Sheldon on "Big Bang Theory". He won't be on this show, but he's narrating it. The kid is played by Iain Armitage, who you probably don't know … yet! Isn’t he adorable?!