Have your team test a simple (clockwise) paper pinwheel and a simple (counterclockwise) paper pinwheel of exactly the same design against exactly the same fan. Coach-type questions to ask: did they work equally well? which design worked best for the fan (blade direction matched fan direction or reversed?) was the same position relative to the fan best for each of them? can you use position to compensate for non-optimal direction? since you don't know if the competition fan will be clockwise or counterclockwise, what does this tell you?
It's about a 15min exercise, and well worth the time.