* Proper nouns are specific names of people, places, or things. They are always capitalized. Examples:
* People: John, Mary, Ms. Smith
* Places: New York City, the Eiffel Tower
* Things: The Great Wall of China, The Mona Lisa
* Second grade is a general term referring to a level of education. It is not a specific name.
Common nouns are general terms for people, places, or things. They are not capitalized unless they start a sentence.
Therefore, "second grade" is a common noun.