||Original Air Date
||The Electric Can Opener Fluctuation
||September 21, 2009
||Following the gang returns from the Arctic. Penny is happier than most...More
||The Jiminy Conjecture
||September 28, 2009
||The episode begins with Sheldon, Howard and Raj in the comic book store, the first two arguing about comics. Leonard arrives and the others are surprised he is not with Penny. As Wolowitz and Koothrappali pry a little more, they discover Leonard is not as happy with the sex.
||The Gothowitz Deviation
||October 5, 2009
||After a sexual encounter that results in Penny's bed breaking, Penny and Leonard end up sleeping in Leonard's room, much to Sheldon's dismay. Raj and Howard go to a goth bar to meet girls.
||The Pirate Solution
||October 12, 2009
||Raj must find a new job or be sent back to India. Sheldon has a solution, which is to allow Raj to work "for" him, rather than work "with" him. Raj reluctantly accepts the offer. With Raj working for Sheldon, it makes Howard lonely, so he tries to stay with Leonard and Penny.
||The Creepy Candy Coating Corollary
||October 19, 2009
||Sheldon enters a trading-card competition upon learning that Wil Wheaton, who he hates for not coming to a sci-fi convention he went to, will also be attending. Howard has a blind date with a girl named Bernadette.
||The Cornhusker Vortex
||November 2, 2009
||Sheldon, who grew up in Texas where it was popular, teaches Leonard how to understand football so that he can try to fit in with Penny's friends. During the game Leonard attempts to demonstrate what he has learned, but his explanations are too clinical, and he fails to fit in.
||The Guitarist Amplification
||November 9, 2009
||An argument between Leonard and Penny proves "inconvenient" to Sheldon. We learn that Sheldon's parents argued a lot when he was growing up, and he doesn't like to hear people arguing at all.
||The Adhesive Duck Deficiency
||November 16, 2009
||Leonard is with Rajesh and Howard on a camping trip to watch the Leonid Meteor Shower, but all three succumb to 'magic' cookies they get from Deadhead campers nearby. Sheldon comes to Penny's rescue when she slips in the tub and hurts her shoulder.
||The Vengeance Formulation
||November 23, 2009
||Wolowitz's new girlfriend, Bernadette, asks him where their relationship is going after their third date. He avoids her for a week, thinking about whether he should "settle" for her or hold out for the impossible (a hot girl from a sci-fi series being interested in him).
||The Gorilla Experiment
||December 7, 2009
||Bernadette, in the guys' apartment for dinner, shows an interest in physics, particularly in the work that Leonard is conducting. Leonard offers her the chance to watch him conduct an experiment at work. Wolowitz is jealous of this and accuses Leonard of being interested in Bernadette. Noticing Bernadette's attention, Penny asks Sheldon to teach her a little physics.
||The Maternal Congruence
||December 14, 2009
||A visit from Leonard's mother, Dr. Beverly Hofstadter (Christine Baranski), delights Sheldon and horrifies Leonard. Penny is upset because Leonard didn't mention his mother's visit to her.
||The Psychic Vortex
||January 11, 2010
||Sheldon and Koothrappali attend a university mixer. They meet Abby (Danica McKellar), who takes a liking to Raj, and her friend Martha (Jen Drohan), who they go on a couple of dates with. Leonard has troubling dealing with Penny believing in psychics.
||The Bozeman Reaction
||January 18, 2010
||When their apartment is robbed and their TV, video games, and computers are stolen, Leonard and Sheldon turn to Howard to create a state-of-the-art security system, which includes an electrified net over the door. Sheldon gets caught in that net and decides he needs to leave Pasadena.
||The Einstein Approximation
||February 1, 2010
||Sheldon's search for the answer to a physics problem keeps him up all night for several days and he becomes obsessed with finding the answer. One attempt in a mall ballpit has Leonard jump in and try to get Sheldon out as he pops in and out, shouting "Bazinga!".
||The Large Hadron Collision
||February 8, 2010
||Leonard announces that the professor who was invited to a trip to see CERN's Large Hadron Collider in Switzerland was unable to go, so he (Leonard) was designated to be the replacement to go to Switzerland, and he gets to take one guest with him. Sheldon assumes that he is going.
||The Excelsior Acquisition
||March 1, 2010
||Sheldon misses his chance to meet comic book legend Stan Lee when he has to attend traffic court after receiving a ticket because of Penny. The ticket was a camera shot of Sheldon running a red light in Penny's car when he was taking her to the hospital in 'The Adhesive Duck Deficiency'.
||The Precious Fragmentation
||March 8, 2010
||On the way to buy Chinese food, the guys see someone that looks like Adam West and follow him to a garage sale, where they buy a box of merchandise for 60 dollars. They ignore Penny's anger at not getting food, and among other things they find a 'Lord of the Rings' ring.
||The Pants Alternative
||March 22, 2010
||Sheldon's friends come to his aid when his fear of public speaking stands between him and a coveted award.
||The Wheaton Recurrence
||April 12 2010
||One night after making love, Leonard surprises Penny by saying "I Love You" but she can only say "thank you" and they both start to think about where their relationship is heading. The next day, Penny and the guys are in a bowling match with Stuart and the gang from the comic book store.
||The Spaghetti Catalyst
||May 3, 2010
||Leonard and Penny have broken up. Sheldon meets Penny in the hall and invites himself to visit her in an hour for spaghetti with hot dogs.
||The Plimpton Stimulation
||May 10, 2010
||Dr. Elizabeth Plimpton (Judy Greer), a cosmological physicist from Princeton University who sleeps Leonard and Raj. Penny shows her jealousy.
||The Staircase Implementation
||May 17, 2010
||Leonard tells Penny the story of how he first met Sheldon. The meeting involved an elevator. This episode is mostly in flashback.
||The Lunar Excitation
||May 24, 2010
||The guys set up an experiment on the building's roof to bounce a laser off the moon and back to Earth. Leonard thinks Penny might enjoy that, so he goes to get her, only to find she has male company. Penny and her date accompany them to the roof to observe the experiment. However, in the course of doing so, Penny's date demonstrates himself to be extraordinarily dim witted. Raj and Howard sign up Sheldon for on-line dating and they match him with Dr. Amy Farrah Fowler.