Some teachers can be mean and some can be nice. If there nice I respect them if there mean I don't. If they shout a lot or just come in angrily most classes just automatically dislike them
Actually, it totally depends on the teacher's behaviour if the teacher is nice everyone will like and respect them, but if the teacher is mean nobody will like or respect.
Snapchat itself is not inappropriate, it's down to who you are using it with and what you are using it for.
I use Snapchat in an entirely innocent way. But some girls in my class have older boys in their Snapchat contacts, and they send them nude Snapchat images.