The gang discovers Penny has been taking a history class at Pasadena Community College in hopes of giving herself more options than waiting tables and acting. The disparity between Penny's and Leonard's education is often a sore point. I'm glad Penny's motivation in this episode was not simply to try and catch up.
Leonard responded encouragingly, offering to help with Penny's first paper, but Penny said it was important that she succeed or fail on her own merit. She forbade Leonard to read her paper, but curiosity got the better of him, and he read it anyway. His dilemma then became how to help Penny without revealing he read the paper. I would have liked to see the rest of the gang come up with a scheme to help, but Sheldon was preoccupied playing Words With Friends with Stephen Hawking.
In the end, Penny had a moment of triumph, waving a B- in Leonard's face, but seconds later we see that Amy and Bernadette rewrote the paper for her, under pressure to remain friends. I get the comedy, but I hope Penny does find fresh interests in college, perhaps a career choice the writers didn't anticipate. Can you tell I was a teacher?