The Platonic Permutation (S09, Ep9)

Sheldon and Amy try hanging out as friends when they spend Thanksgiving together at the Aquarium.

21m

The Earworm Reverberation (S09, Ep10)

After his desperate attempts to remember the name of a song stuck in his head, Sheldon has a revelation.

21m

The Opening Night Excitation (S09, Ep11)

After more than five years of dating, Sheldon and Amy spend their first night together.

21m

The Sales Call Sublimation (S09, Ep12)

Penny gets more than she bargained for when Leonard agrees to meet with a psychiatrist on her behalf.

18m

The Empathy Optimization (S09, Ep13)

After having to deal with Sheldon being sick, Leonard, Penny and the gang try to treat themselves.

19m

The Meemaw Materialization (S09, Ep14)

Sheldon's thrilled when his Meemaw comes to visit, but his excitement fades when she butts heads with Amy.

19m

The Valentino Submergence (S09, Ep15)

Sheldon and Amy host a special live Valentine's Day episode of "Fun with Flags."

20m

The Positive Negative Reaction (S09, Ep16)

When the gang finds out about Bernadette's pregnancy, they celebrate by singing karaoke.

19m

The Celebration Experimentation (S09, Ep17)

After more than nine years together, the gang finally celebrates Sheldon's birthday with a few special guests.

19m

The Application Deterioration (S09, Ep18)

Penny, Amy and Bernadette give Raj dating advice.

19m

The Soldier Excursion Diversion (S09, Ep19)

When Sheldon's laptop dies, it leads him to share a deep secret with Amy. Raj sells out Leonard and Howard.

21m

The Big Bear Precipitation (S09, Ep20)

Sheldon spills a secret of Leonard's when the two take a weekend cabin trip with Penny and Amy.

19m

The Viewing Party Combustion (S09, Ep21)

When a small argument between Leonard and Sheldon erupts into a heated fight, everyone must take sides.

18m

The Fermentation Bifurcation (S09, Ep22)

The gang goes to a wine bar and runs into Penny's old boyfriend, Zack; Bernadette gets stuck.

20m

The Line Substitution Solution (S09, Ep23)

Sheldon hires Stuart to spend the day with Amy when he'd rather go to a movie screening.

18m

The Convergence Convergence (S09, Ep24)

Leonard's recently divorced parents and Sheldon's devoutly religious mother come to town.

20m