I know there's a book that shows 200 different ways of how to verify the theory behind pythagoras. Maybe that's interesting for your essay? You can find it all on internet : http://www.wisfaq.nl/showfaq3.asp?id=7289 You've only got to translate it to your language:P This are only 5 ways, can you imagine 200 ways....
Maybe things about the men who figured pythagoras out is also interesting?