class period vs course of study

class period and course of study both are nouns.

Word	Noun	Adjective	Verb	Adverb
class period	Yes	No	No	No
course of study	Yes	No	No	No

class period (noun)	course of study (noun)
a regularly scheduled session as part of a course of study	education imparted in a series of lessons or meetings
	an integrated course of academic studies