What is the coolest science fair project ever?

What is a good high school science fair project that is easy but original and does not cost much?

• I have to have an idea of a science fair project by halloween. Our school has a prestigious science department and, for better or worse, it is mandatory that I enter due to the fact that I'm in Honors Chemistry. I have never participated in a science fair before and our instructor says that it can't be a project that has been done a million times in the past unless there is an original spin on it. If you do give me an idea, please include instructions as well. Thanks.

• Answer:

  i did one before that was interesting but really inexpensive you can even make it much much better,by adding and researching.. it deals with the principal of aerodynamics or the force of lift, drag,thrust and velocity all you have to do is get a cardboard regular cardboard those that are sold in the book supplies stores($65cents)(ex:STAPLES) paper($1) Marker sharpie($1),measuring tape or ruler($99 cents dollar store) and a watch that recors time($1 dollar store) or your regular handwatch which record seconds what you have to do though is make five paper airplanes of different designs and make a reference point from where you are going to toss them..you have to throw them with the same force ,measure the distance traveled,estimate the height of each one of them,record the one's that flyed the least and the ones that flied fast. explain why different designs flyed more than others? the Airfoil Shape theory ?(google.com) how weight has effect on them?