"Your" is what's called a possessive pronoun. But if you are a "teacher", as you tell people, why do I have to tell you this?
If you intend to say "You are", it's spelled "you're" and is called a contraction.
Here are examples of both usages:
"This is your mistake".
"You're not very good at grammar, and shouldn't be teaching our children".
Here are examples of both usages:
"This is your mistake".
"You're not very good at grammar, and shouldn't be teaching our children".