I was planning on saving this for my son’s science fair (he is 9), but we can all enjoy this simple project. Go to a beach….have fun and go swim. Day two, set up some banners directly on the beach….I’m thinking bright green (the color is really up to you, and won’t effect the experiment). Rent a boat…or borrow, or steal….whatever. Take your GPS…now you may need to buy one because your cellphone probably won’t work. Go about 8 miles out to sea (I will be doing lake Erie because I live in Ohio.). Get out your binoculars, if you don’t own any just go to Walmart and buy some. If you can see the banner on the beach….then the world is flat….if not….well it isn’t. I don’t think I can make this any simpler. It has to be done over water because the earth terrain is not flat. Water is held down with gravity….or is it! (Lol, it is)