The kids I work with in my class a 11,12,13 years old. It sometimes is hard for me to believe most have never picked up a hammer or even no the difference between a flat or phillips head screw driver. When I first started teaching, I assumed way to much out of them. Like Frank said accuracy and control is their biggest problem. I only get them 1 hour a day twice a week so it is hard to get much done once they get their fires lit.The first couple classes I have them just beat some 1/2" square bar into submission as hard as they can and do what ever they want. At this time I also explain the cow poop theory which I like and they seem to also, lot of giggles. Next I will have them take and flaten the end out into the biggest, thinest even mass they can. Then we start on making nails, were they need to learn the control. Seems to work.