Here's why:
* Common nouns refer to general, non-specific people, places, or things.
* Proper nouns refer to specific people, places, or things (and are capitalized).
Since "pupils" refers to students in general, it is a common noun.
Here's why:
* Common nouns refer to general, non-specific people, places, or things.
* Proper nouns refer to specific people, places, or things (and are capitalized).
Since "pupils" refers to students in general, it is a common noun.