P.R.
Our son went to the State Science Fair with his idea of how a hydroplane works. That was many years ago, so my memory may not serve me right, but I am pretty sure it was a hydroplane. He had so much fun doing his research, and the other kids in his class enjoyed learning from his project. I think he was in 4th grade at the time. He is in college, now, working on a Master of Electrical Engineering degree.