Credit to JHC for the Turing Fork battery idea.
A series of strategies to generate power from your nearest educational establishment, mostly based upon magnets and coils concealed in various items.
1) First would be the ones concealed in marker pens and board rubbers
2) secondary market in tweed
jackets sleeves (to extract power from arm waving)
3) thirdly the issue of hats to scholars, which take advantage of the students nodding off during lectures
and the most tricky one to harness,
4) the speeding piece of chalk going across the classroom of a school. Suspect would work better with piezo to harness the impact rather than iron core in the chalk and large coil surrounding the classroom.
5) might be piezo-electric trousers, for the more traditional minded public schools, if any of them do caning these days. "This hurts me more than it does you" (subtext - I have to recharge my iPhone).