This was an AP physics class. I'd also won a "longest time in air" glider thing by departing from the norm. Instead of going for distance, I made a cupped lifting body that glided down a bit, nosed up, lifted into a leisurely hang of a stall, dipped its nose and regained airspeed, pitched back up at a certain speed, stalled again, and repeated that all the way to the ground, taking a long time to do it. Shortest distance, but longest time in air. :)