Answering this has two steps. First, you must define what a bureaucratic organization is. Then, you must look at your school and find evidence for and against the idea that it is a bureaucratic organization.
A bureaucratic organization is typically defined as a hierarchical organization in which officials carry out the rules that and procedures that have been handed down to them by higher authority.
Schools are like this in some ways but not in others. Teachers typically have to implement procedures and rules that have been handed to them by principals or by school boards. On the other hand, teachers have a great deal of discretion in how they go about doing their jobs each day.
To answer this question, then, give a definition of a bureaucratic organization and try to think of as much evidence as you can for whether your school is such an organization.