This is a very broad topic. I think that the first step that has to be taken in forming any thesis statement would be to ensure that what you are going to write about is consistent with the evidence and analysis that you possess. Bearing this in mind, I would strongly suggest that you analyze what you have in your possession and what you are going to use as referential points in your paper. As you survey the topics at hand, what are you going to argue in terms of the purpose of education, or pedagogy, or classroom management? You should have some findings or data that would help guide you to forming a belief on these areas, and this can become the thesis statement that you will enhance and prove in the course of your paper.