Strictly speaking, this does not constitute an
experiment - rather, it is a work of
drama; a play to be
acted out.
Were it an actual scientific experiment, it would have to be administered in a double-blind fashion. As described here, the teacher (experimenter) is likely to unduly influence the results by imposing his/her own values and preconceptions. Likewise, as stated by DoctorNo, the subjects of the "experiment" can also impose their own values and opinions on the outcome.
The only thing this fabricated social drama proves decisively is that humans, like many other mammals, have a strong urge to establish hierarchy and "pecking order".