If you go to Flatpoint High, you could make a superconductor out of soup cans. Or make a battery out of poo. Seriously, though, the best projects I did started with a common problem or question. Think of things that interest you, and facts you know about them, then take it a step farther by asking, "If we know that (blah) does (blah), then what would (blah-blah) do under these conditions?" Use the scientific method and form your experiment. Gather your data, then analyze it and determine the answer. Often hypotheses that are proven incorrect through proper research and experimentation can still be winning science fair material, provided you do everything correctly and explain yourself well.