Young Sheldon showed the origins of the Periodic Table game, but this version has different rules than the one he played with Penny in The Big Bang Theory. The CBS spin-off continues to build on the socially inept genius’ story beyond the events in The Big Bang Theory — but instead of simply continuing his arc in modern times, Young Sheldon is a prequel set when Sheldon was still living in Texas with his family.
Currently in its fourth season, Young Sheldon is tackling its titular character’s first year in college at East Texas Tech. Ever since he started classes at his new school, many of the episodes have been about his adventures as a freshman. That all changed in episode 13 titled “The Geezer Bus and a New Model for Education”; starting with a minor car accident that gave him trauma, Sheldon had a difficult time riding another vehicle again. This hindered him from attending classes. While East Texas Tech was more than willing to accommodate his situation by providing lectures over the phone, it was clear that he would have to get over his fear sooner or later.
Thanks to his mother Mary Sheldon’s fear of car rides didn’t last very long. At the end of the same Young Sheldon episode, he was back on the road with his mom on his way to school. Mary tried to ease her son’s obvious concern by suggesting that they play a game for distraction; Sheldon obliged and came up with the Periodic Table game where they name elements in alphabetic order. The narration during this scene mentioned that this tradition carried over to his Pasadena days as he and Leonard play the same thing. However, this was never shown on-screen in The Big Bang Theory; a different version of the same game was played with Penny instead in season 2, episode 5 titled “The Euclid Alternative.” In the outing, Sheldon asked Penny to drive him to work while Leonard was still asleep. On their commute, Sheldon said they should play a game wherein he names an element, then she follows it up with another one that starts with the last letter from the last one, and vice-versa.
Noticeably, this version of the Periodic Table game was much more difficult compared to when Sheldon played it with Mary in Young Sheldon. If he did play the game with Leonard off-screen just to justify the narration in Young Sheldon, they may have made things a little bit more challenging by tweaking the rules, hence the last letter rule. However, it doesn’t make sense that he would abide by the same guidelines with Penny considering that she’s not exactly scientifically inclined like the rest of his Pasadena friends. If anything, Sheldon should’ve used the original version of the game knowing that both his mom and Penny have around the same amount of knowledge when it came to elements.
Considering how demeaning Sheldon’s behavior was in The Big Bang Theory when it came to Penny and her lack of academic achievements, it’s odd that he would even suggest that they play a more difficult version of the Periodic Table game. On the flip side, this highlights just how patient and understanding she has been with him, particularly in the earlier seasons of the show. In Young Sheldon, only his mother can tolerate him in the same way.