invention ----in my opinion ,invention is to made sth.that no one has ever done before creation----improving/changing/add new ideas to something which already exists both need prototyping(test again again and again until it succeed. i think you could write sth.about history of inventing/creating stuff(e.g.Thomas Edison...or the industrial revolution) and link with today's society,you could discuss has the human civilization progressed much?things like that:D Hope this help:) good luck!
