see thats a great topic, you can explain why you choose it, why you feal qualified to explain it, its naturally intresting etc.
aim for 500 to 600 words, or 30 'points' that you want to get across, I always find it much easyer to write presentations like this, because they shouldn't just be a paragraph of text that you'd submit for an essay.
great topic, wish the munchkins who'd i'd had to sit through where so intresting (seriously one person did a 10 minuite feature on suping up a corsa, i mean get a girlfriend or lean how to rubbishrubbishrubbishrubbish please, that was unbearable!)