Possible Clues:

• Expected grade in a gut course
• "Rocks for Jocks" type of class
• Breezy class
• Hardly a tough course
• Smooth-sailing source
• No-brainer class, an example of which is named by combining the ends of 20-, 36-, 42- and 55-Across
• You hardly have to study for it
• Class that requires no effort to pass
• Class that requires little effort to pass
• 2010 Emma Stone movie