In his Critique of Pure Reason, Immanuel Kant discusses what makes up identity. He suggests that identity comes from self-consciousness and that self-consciousness arises from a combination of ideas that a person calls their own. This combination of ideas arises as a result of understanding how things are related. This seems to mean that the more people relate different ideas in the same ways the more similar their personal identities.
So how does this factor into schooling? Schools are institutions in which students are taught to make connections in a specific way. For example, we learn relations between letters and words, colors and objects, reprimands or rewards and actions, etc. Everyone is taught to make these same connections. Furthermore, many schools are restrictive and do not allow for deviance. For example, in math class, a student may discover a new way to solve a problem, one that is different from the way the teacher explained. Although the student came up with the correct answer, the teacher reprimands the student, or takes points off a test because it was not the “right” way to solve the problem. This reinforces connections the teacher made earlier between the idea of correctness and her method of solving the problem.
I believe this shows the limiting effect of schooling. It creates fewer differences between the ways in which people combine their ideas and therefore fewer differences in identity.