Schools of education are criticized for not adequately preparing new teachers for the realities of the classroom. The closest they come to doing so is student teaching. Typically, this means teaching one class a day for two semesters under the supervision of a licensed teacher.
I'd like to propose an intermediate step that schools of medicine use with their new interns. Before interns are allowed to attend to real patients, they practice on artificial ones ("Chicago's Intern 'Boot Camp' Is a Rehearsal for Life or Death Medic...," The New York Times, Jul. 15). The rationale is that errors made on the latter do not cause harm to the former.