How do I ignore annoying people?

In my english class there are some annoying people who pretend to be my friend and be nice to me, constantly asking me questions to find out about me and my friends.
I told one of the girls today that I wasn't her friend but they keep annoying me, they're just using me to find out about people they don't like in our year group.
Oh yeah, they're also in my Spanish, history, music, RS and geography class but some are also in maths and science.

Any help to ignore these people please?

(Other than telling a teacher, because our school isn't good at handling things related to bullying.)

You just need to block them out really, learn to say no. It sounds like they are trying to use you to help them with their work or for gossip, you probably know it yourself but don't let them take advantage of you. If they ask, just say "I don't know".