Question

Why would you use tú when speaking to a classmate?

Answer 1

You would use “tú” when speaking to a classmate because they are the same age as you and you can be informal with them. But it it was a teacher or someone “higher” than you you would use “usted”

Answer 2

Tu is informal

Step-by-step explanation:

you would use usted if talk to someone you barely know but a classmate you would use tu because it is less formal