Dear Menahil,
If you want your best friend sit with you in the classroom, you'd better discuss with your teacher or the person who can be helpful to you in this regard. However it may be good for you because sitting with her can cause problems for you. Usually friend sitting together engage talking with one another and lose their interest in the lesson. Sometimes we depend on our friend's accomplishments; it leads us to laziness and dull attitude. Let the situation be there. It may benefit you.