New teachers need to have a mentor because they need someone that can point out flaws that need improved in order to improve the teaching in the classroom. These experienced teachers have seen methods that have worked and not worked in the classroom. They can expedite the new teachers process of what good classroom management skills to try, etc. They are answering your questions from experience, which is what the new teachers will lack. Having a person from the field giving advice would personally make me feel more confident when I am working with students in the classroom by myself.