- 1 The Electric Can Opener Fluctuation
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When Sheldon learns the guys tampered with his expedition data he got from the arctic, he leaves to Texas in disgrace. This results in the guys following him, which threatens Leonard's hope for some romantic time with Penny and the guys' friendship with Sheldon.
Average Episode Rating: 4.3 | Air Date: 2009-09-21
- 2 The Jiminy Conjecture
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Leonard and Penny struggle to recover from an awkward first hookup while Sheldon and Howard stake their best comic books on a bet to determine the species of a cricket.
Average Episode Rating: 4.3 | Air Date: 2009-09-28
- 3 The Gothowitz Deviation
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Howard and Raj visit a Goth nightclub to pick up women while Sheldon attempts to build a better Penny using chocolate-based behavior modification.
Average Episode Rating: 4.3 | Air Date: 2009-10-05
- 4 The Pirate Solution
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Raj must find a new job or be sent back to India, but Sheldon has a solution, which leaves Leonard and Penny dealing with Howard as a third wheel.
Average Episode Rating: 4.3 | Air Date: 2009-10-12
- 5 The Creepy Candy Coating Corollary
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After overhearing that Wil Wheaton is entering a trading-card competition, Sheldon decides to enter it himself. Meanwhile, Penny sets up one of her friends on a date with Wolowitz.
Average Episode Rating: 4.4 | Air Date: 2009-10-19
- 6 The Cornhusker Vortex
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Sheldon becomes Leonard's teacher in order to understand football, while an incident with flying a kite threatens Howard and Raj's friendship.
Average Episode Rating: 4.5 | Air Date: 2009-11-02
- 7 The Guitarist Amplification
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A squabble between Leonard and Penny sees Sheldon playing mediator, though out of his own incovenience from the sitiation rather than altruism.
Average Episode Rating: 3.7 | Air Date: 2009-11-09
- 8 The Adhesive Duck Deficiency
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With Leonard, Howard and Raj away camping in the desert, an injured Penny has only Sheldon to rely on.
Average Episode Rating: 4.4 | Air Date: 2009-11-16
- 9 The Vengeance Formulation
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After he's humiliated on National Public Radio, Sheldon vows to destroy Kripke, while Wolowitz tries not to destroy his new relationship with Bernadette.
Average Episode Rating: 4.3 | Air Date: 2009-11-23
- 10 The Gorilla Experiment
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Penny gets help from Sheldon in order to understand what Leonard's work is, while Wolowitz develops a jealousy when Leonard starts hanging out with his new girlfriend.
Average Episode Rating: 4.4 | Air Date: 2009-12-07
- 11 The Maternal Congruence
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A Christmas visit from his mother has Leonard discovering she's kept a lot of news from him that she shares with Sheldon and worrying if she'll approve of his romance with Penny.
Average Episode Rating: 4.4 | Air Date: 2009-12-14
- 12 The Psychic Vortex
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Leonard is aghast to find out a secret of Penny's: she believes in psychics. Meanwhile, Sheldon tries to assist Koothrappali in picking up a girl at a university mixer.
Average Episode Rating: 4.3 | Air Date: 2010-01-11
- 13 The Bozeman Reaction
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When their apartment is robbed, Leonard and Sheldon turn to their friends to create a state-of-the-art security system.
Average Episode Rating: 4.6 | Air Date: 2010-01-18
- 14 The Einstein Approximation
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Sheldon's search for the answer to a physics problem leads him to work at the Cheesecake Factory with Penny.
Average Episode Rating: 4.3 | Air Date: 2010-02-01
- 15 The Large Hadron Collision
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Leonard can only bring one guest on a trip to see CERN's Large Hadron Collider (the world's largest and highest energy particle accelerator) in Switzerland on Valentine's Day.
Average Episode Rating: 4.3 | Air Date: 2010-02-08
- 16 The Excelsior Acquisition
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Sheldon winds up in traffic court when he gets a ticket because of Penny.
Average Episode Rating: 4.4 | Air Date: 2010-03-01
- 17 The Precious Fragmentation
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When the guys find a ring from "The Lord of the Rings" at a garage sale, it threatens to tear them apart.
Average Episode Rating: 4.6 | Air Date: 2010-03-08
- 18 The Pants Alternative
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Sheldon's friends come to his aid when his fear of public speaking stands between him and a coveted award.
Average Episode Rating: 4.8 | Air Date: 2010-03-22
- 19 The Wheaton Recurrence
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A fight between Leonard and Penny threatens their relationship, while Sheldon battles Wil Wheaton in bowling.
Average Episode Rating: 4.1 | Air Date: 2010-04-12
- 20 The Spaghetti Catalyst
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When Leonard and Penny aren't speaking, Sheldon goes to extremes to keep them both happy.
Average Episode Rating: 4.3 | Air Date: 2010-05-03
- 21 The Plimpton Stimulation
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Leonard and Sheldon compete for the attention of a famous female physicist.
Average Episode Rating: 4.1 | Air Date: 2010-05-10
- 22 The Staircase Implementation
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Leonard tells Penny about how he met Sheldon for the first time...and what happened to the elevator.
Average Episode Rating: 4.9 | Air Date: 2010-05-17
- 23 The Lunar Excitation
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While Penny worries that dating Leonard has ruined her for normal guys, Wolowitz and Koothrappali search for Sheldon's perfect match online.
Average Episode Rating: 4.4 | Air Date: 2010-05-24