Maybe a pedal powered axial flux alternator might get a better response from the school?
You can still learn a huge amount from building one of the alternators, a few have tried it here on fieldlines.
Search forum member 'Dinges' files.
Also:
As a detention duty, rather than scribbling 'lines' on a blackboard the punishment may be 30 minutes power generation on a pedal generator - that would deter me from misbehaving again, and give you some power into a battery bank.
Ben.