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

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

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

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

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

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

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

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

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.

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

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

While Sheldon and Koothrappali attend a university mixer, Leonard is upset to discover that Penny believes in psychics.

A visit from Leonard’s mother delights Sheldon and horrifies Leonard.

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.

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