0Prfesser 9 years ago A question you need to answer for yourself: are you just trying to complete an assignment, or are you actually trying to win a science fair? If you're just trying to complete an assignment, there are lots of projects on the web, one of which Jack A Lopez mentioned. Pick one that's easy, build it, get your grade. OTOH if you want to win a proper science fair, you have to do what scientists actually DO... which is "provide new knowledge". Which is done as Kelseymh says; hypothesis-test-repeat. Many years ago I judged a regional fair that was won by a young woman who had studied (believe it or not) the flammability of different types of dryer lint. She won because: she had a genuine interest in what she was doing; she had done rigorous studies over a two-year period; her conclusions were fully justified with proper statistics. At many science fairs, the project that wins is not the showiest, not the prettiest, not even the most ingenious. It's the process, not the product. It's the one that showed that the winner knew how science is done----and did it. So: if you're into winning, learn how science is really done. Then find something you're truly interested in, and do science.