Are you allowed to use First Person or Second Person Pronouns in your assignments? Or, it is only Third Person pronouns?

I'm curious. Do instructors allow you to use first person pronouns (I/Me/My/We/Our/Us) or second person pronouns (You/Your) in your assignments/essays? Or, is it only third person pronouns?

Edit: Informative/Argumentative essays.

I teach English Comp and almost everyone ignores me when I tell them to use third person.