E20 • The Spaghetti Catalyst

E1 • The Electric Can Opener Fluctuation

When Sheldon learns that 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.

21m • 2009

When Sheldon learns that 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.

E2 • The Jiminy Conjecture

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.

20m • 2009

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.

E3 • The Gothowitz Deviation

Howard and Raj visit a Goth nightclub to pick up women while Sheldon attempts to build a better Penny using chocolate-based behavior modification.

20m • 2009

Howard and Raj visit a Goth nightclub to pick up women while Sheldon attempts to build a better Penny using chocolate-based behavior modification.

E4 • The Pirate Solution

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.

20m • 2009

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.

E5 • The Creepy Candy Coating Corollary

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.

20m • 2009

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.

E6 • The Cornhusker Vortex

Sheldon becomes Leonard's teacher in order to understand football, while an incident with flying a kite threatens Howard and Raj's friendship.

19m • 2009

Sheldon becomes Leonard's teacher in order to understand football, while an incident with flying a kite threatens Howard and Raj's friendship.

E7 • The Guitarist Amplification

A squabble between Leonard and Penny sees Sheldon playing mediator, though out of his own incovenience from the sitiation rather than altruism.

19m • 2009

A squabble between Leonard and Penny sees Sheldon playing mediator, though out of his own incovenience from the sitiation rather than altruism.

E8 • The Adhesive Duck Deficiency

With Leonard, Howard and Raj away camping in the desert, an injured Penny has only Sheldon to rely on.

20m • 2009

With Leonard, Howard and Raj away camping in the desert, an injured Penny has only Sheldon to rely on.

E9 • The Vengeance Formulation

After he's humiliated on National Public Radio, Sheldon vows to destroy Kripke, while Wolowitz tries not to destroy his new relationship with Bernadette.

18m • 2009

After he's humiliated on National Public Radio, Sheldon vows to destroy Kripke, while Wolowitz tries not to destroy his new relationship with Bernadette.

E10 • The Gorilla Experiment

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.

20m • 2009

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.

E11 • The Maternal Congruence

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.

19m • 2009

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.

E12 • The Psychic Vortex

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.

19m • 2009

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.

E13 • The Bozeman Reaction

When their apartment is robbed, Leonard and Sheldon turn to their friends to create a state-of-the-art security system.

19m • 2009

When their apartment is robbed, Leonard and Sheldon turn to their friends to create a state-of-the-art security system.

E14 • The Einstein Approximation

Sheldon's search for the answer to a physics problem leads him to work at the Cheesecake Factory with Penny.

18m • 2009

Sheldon's search for the answer to a physics problem leads him to work at the Cheesecake Factory with Penny.

E15 • The Large Hadron Collision

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.

20m • 2009

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.

E16 • The Excelsior Acquisition

Sheldon winds up in traffic court when he gets a ticket because of Penny.

20m • 2009

Sheldon winds up in traffic court when he gets a ticket because of Penny.

E17 • The Precious Fragmentation

When the guys find a ring from 'The Lord of the Rings' at a garage sale, it threatens to tear them apart.

20m • 2009

When the guys find a ring from 'The Lord of the Rings' at a garage sale, it threatens to tear them apart.

E18 • The Pants Alternative

Sheldon's friends come to his aid when his fear of public speaking stands between him and a coveted award.

20m • 2009

Sheldon's friends come to his aid when his fear of public speaking stands between him and a coveted award.

E19 • The Wheaton Recurrence

A fight between Leonard and Penny threatens their relationship, while Sheldon battles Wil Wheaton in bowling.

20m • 2009

A fight between Leonard and Penny threatens their relationship, while Sheldon battles Wil Wheaton in bowling.

E20 • The Spaghetti Catalyst

When Leonard and Penny aren't speaking, Sheldon goes to extremes to keep them both happy.

19m • 2009

When Leonard and Penny aren't speaking, Sheldon goes to extremes to keep them both happy.

E21 • The Plimpton Stimulation

Leonard and Sheldon compete for the attention of a famous female physicist.

20m • 2009

Leonard and Sheldon compete for the attention of a famous female physicist.

E22 • The Staircase Implementation

Leonard tells Penny about how he met Sheldon for the first time...and what happened to the elevator.

19m • 2009

Leonard tells Penny about how he met Sheldon for the first time...and what happened to the elevator.

E23 • The Lunar Excitation

While Penny worries that dating Leonard has ruined her for normal guys, Wolowitz and Koothrappali search for Sheldon's perfect match online.

19m • 2009

While Penny worries that dating Leonard has ruined her for normal guys, Wolowitz and Koothrappali search for Sheldon's perfect match online.