Raj and Penny are doing yoga. Raj asks Leonard to take Cinnamon for a walk. 

Amy is working on an experiment to determine when we consciously make decisions. Sheldon takes an interest in it and wants to combine his calculations with her experiments. 

Amy and Sheldon agree to collaborate, but need to establish a few ground rules. 

Raj and Penny are clearly establishing a relationship that is making Leonard uncomfortable and feeling left out. 

Amy and Sheldon agree to work together, combining physics and biology. 

Leonard goes to Target with Howard and Bernadette to complain about Penny and Raj. 

Amy and Sheldon realize their collaboration did not work,, causing tension between them. They realize their fighting is actually helping. 

Leonard admits to Penny and Raj that he has been feeling left out. 

Amy and Sheldon revise their ground rules to allow them to insult each other for the sake of science, even if it might be detrimental to their relationship.