Corrrect use of word "in" vs "at" in a sentence

Corrrect use of word "in" vs "at" in a sentence

hi, Hi, can someboby could me help with de the correct use of the prepositions, word "in" vs "at"?

In most cases, the easiest way to remember is that, "in" denotes the exact physical space which means inside something.  "You are in class".  This means that you are physically INSIDE the classroom and no where else.  "You are at class".  This means you MAY be physicall inside the classroom but you may not.  You could  be just in other parts of the school going to your class.

For abstract concepts...  "You are in love" but "you are at love" is wrong.