"Environmental Science" aired on November 19th, 2009. It was written by Zach Paez, and directed by Seth Gordon.
PlotEditSeñor Chang has been assigning outrageous amounts of homework, and the group volunteers Jeff to ask him to stop. When Jeff goes to talk to him, he finds out that Señor Chang is having marital problems, and ends up befriending him (for his own personal gain).
Troy and Abed are biology partners. Their project is to teach a mouse to respond to a song, but Troy is afraid of mice. When the mouse gets loose, he tries to hide from Abed, so that he doesn't have to help search for it.
Shirley is nervous about giving a speech in her marketing class and has Pierce help her with her presentation.
At the school's Earth Day dance, everybody's dilemmas are solved, when Jeff gets Señor Chang and his wife back together, Troy and Abed find their mouse, and Shirley overcomes her fear of public speaking.