Merriam-Webster's 11th Collegiate Dictionary lists the meanings of "class" as follows:
a: a body of students meeting regularly to study the same subject
b : the period during which such a body meets
c : a course of instruction
d : a body of students or alumni whose year of graduation is the same.
Could you please give sentence examples conveying the different meanings above?
Class is one of those fun (?) English words that have lots of different meanings. In general, a class is a group of things that have an attribute in common. That's how you get "upper class" people (and social classes) and why the USS Enterprise is a "Constitution class" starship.
That's also why it makes sense to use "class" as a term for a group of students who graduated or will graduate in the same year.
"I'm Harvard, Class of 1995."
As Robert said, "class" is also a unit of education. It can be synonymous with "course," meaning a series of sessions in which students are taught one subject [check out our previous Glossary entry for "course"]:
"What classes are you taking next semester?"
"There are 20 other students in my biology class."
"The English department offers classes in modern literature."
"Class" can also mean one single session of instruction [Note: "course" cannot be used in this way]:
"I can't go to the movies, I have class."
"I didn't do the reading for today's history class."
Robert also asked:
Compare the use of "class" and "lesson:"
"Who is teaching the class?" "Who is teaching the lesson?"
A "lesson" is a subdivision of a course of instruction. For example, maybe your English course is broken up into lessons on regular verbs, irregular verbs, adverbs and adjectives.
Because courses are already conveniently divided into separate meetings, it's logical to think of each session as containing one lesson. Lessons don't have to line up with class sessions though ("In today's art class we'll have a lesson on painting and a lesson on sculpting." "Over the next two classes we'll work on lesson 3 in your textbook.").
So in Robert's two examples:
"Who is teaching the class?" is ambiguous and could be asking about one session or the entire course.
"Who is teaching the lesson?" would usually be asking about one session.
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