When Should I Add Apostrophes? - Punctuation for Meaning
ome students confuse plurals, apostrophes, and
contractions.
More than one item is indicated by only plurals, not apostrophes.
For example,
He has two papers due next week. NOT . . . two paper's
Apostrophes indicates possession (except for possessive
pronouns). For example,
My group's high grade made us proud of our effort.
Contractions should not be confused with possessive pronouns.
For example,
What do you mean "You're not going to your 8:30 class
again"?
They're going to their house, not over there.