1. There were no rules on what the 'plane' was supposed to look like. Creativity was encouraged and normally rewarded in this class (I liked the teacher a lot, actually, and was irked also because it was out of character for her to forbid thinking outside the box).
2. It wasn't during a unit on aerodynamics, and in any case, "the motion of air, particularly when it interacts with a moving object" is quite relevant to wads of paper, meteorites, missiles, arrows, helicopters, and various other objects that are not airplanes. It might have been a good opportunity to explore why something like my wad of paper would go farther than most planes, as well as the relative real world advantages of different things.
2. It wasn't during a unit on aerodynamics, and in any case, "the motion of air, particularly when it interacts with a moving object" is quite relevant to wads of paper, meteorites, missiles, arrows, helicopters, and various other objects that are not airplanes. It might have been a good opportunity to explore why something like my wad of paper would go farther than most planes, as well as the relative real world advantages of different things.