What do you think about me bringing a knife to school?
Why did you bring a knife to school?
So I can hurt someone if I need to.
That is completely inappropriate behavior. You should never bring a knife to school, and more importantly, you shouldn't want to hurt your classmates. If you have an issue with someone, you should try to talk through it with them, or get help from a teacher.
I'm never going to hurt them. I just needed to have it on me at all times.
There is no good reason for wanting to be armed while at school. If you feel like you need to protect yourself then maybe you need to talk to your parents about what is going on in school. Otherwise you're just putting other students at risk because it's never appropriate to have a weapon at school.