McDaniel observed that when a BB fired from the Daisy air rifle would hit the big steel flat-washer that McDaniel threw for his student initially, it would make a shallow dent in the washer. The dent would be between a third and a half the diameter of the BB. But as McDaniel lofted the flat washer into the air by balancing it on the third finger of his right hand and then lifting his elbow quickly, he would also impart a spin to the washer with his thumb and forefinger, which would give the washer a very fast spin-rate, such that any BB dents that had been made in it previously would be impossible for the student to see.