After having taught many people to shoot, I've found a universal challenge (in addition to the well-known and documented challenges): It seems that most people have a hard time grasping the idea of charging a semi-auto pistol or rifle.  There is a tendency to want to ease the charging handle (or slide) forward, rather than pulling it all the way back and letting go, so it can fly forward under its own spring tension as should be done.  We demonstrate the technique, and explain why it should be done that way-- the gun operates this way every time it's fired, and it's necessary to let this happen when charging it by hand, so as to ensure a solid lockup of the mechanism prior to firing, and in some cases, to avoid having your fingers bitten by the mechanism.

Still, while doing a team-teaching session this weekend in NRA Basic Pistol, we had a guy cut his finger while charging a MK II pistol.  "It will bite you" I tell them now, "if you don't let go of the slide.  Just let it fly forward."  In my next class it will be an objective to see to it that this doesn't happen again.

It was a very rewarding day, and all the students came away from it satisfied that they had acquired a good basic understanding of the safety principles, of pistols, and of pistol shooting.  The fact that it was a twelve-hour ordeal came to my mind only afterward.  For those who would like the rewarding experience of teaching people to shoot, using proven, time-tested methods, see Joe's post here or contact the NRA about instructor training classes being held near you.