Okie-dokie. So it has to be something you can research a lot?
The development of something might be good (an invention, a cure for something).
Something historical (causes of some event, legacy of some event, what happened in some event).
Something in which you can discuss the impact of something on society at great length (think drink/drugs/sex).
One of those random things that's just interesting: something like something about lying, or trends in gender, or handwriting analysis.
There you go! Methods of teaching handwriting to kids and then you could always bring in handwriting analysis. Alternatively, something about schooling methods/best ways of teaching something (language, music...).
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I'll move to Paris, shoot some heroin, and fǜck with the stars.
You man the island and the cocaine and the elegant cars.