Amy answers Sheldon's proposal.

Leonard gives an embarrassing radio interview.

Amy tries to convince Sheldon he can be easy-going.

Leonard's mom finds a new best friend in Penny.

Penny figures out the "secret" to Sheldon.

Sheldon auditions to be the new Professor Proton.

Sheldon secretly collaborates with Bert on a project.

Sheldon goes behind Leonard and Howard's backs.

The gang flashes back to 2010.

Sheldon and Amy develop a system for wedding planning.

Sheldon plans a special themed dinner for Amy's birthday.

Sheldon and Amy use science to choose Best Man & Maid of Honour.

Penny helps Sheldon figure out his next scientific move.

Raj discovers he's dating a married woman.

Leonard asks his friends for feedback on his novel.

Bernadette gives birth with the gang's help.

Barry Kripke interferes with Sheldon and Amy's wedding plans.

Penny gets the opportunity to host Bill Gates at work when his company wants to partner with her pharmaceutical company.

Leonard runs against Sheldon for President of the Tenants Association.

Penny and Bernadette plan a bachelorette party for Amy.

Penny makes an astronomical discovery.

Sheldon goes to Vegas to win millions for science.

Sheldon visits his older brother Georgie in Texas.

Amy's parents and Sheldon's family arrive for the wedding.