I don't think you need any help with teaching,it sounds like your doing a great job with the boys! I'ts been my observation that hunter-gathers, military and scouts all use the same basic teaching methods. They all have older experianced members that want to pass down essential information and habits to a group of young men or boys in the most effective manner possible. They all start with patterning, providing an example of some one who has mastered the skills and reinforcing that example with stories , respect for elders and traditions. Kids naturally emulate some one they repect and admire, provide a good pattern and your almost asured a good product. In fact that's the biggest problem I see with scouting , lack of good leaders and you have that licked. They also all bring them up gradually marked by rites of passage, awards ect. to a position of leader and teacher so they come full circle. So with your military background you already have a great background to teach fieldcraft ect. As far as hints the two best I've found so far are have fun and hide the lesson, look how bad school does it turns the kids minds right off. Which brings us to the big gun immediate need it works wonders. Which is another reason school fails becouse with the exception of tests theirs no immediate need for the knowlege. If you teach them something important , let them practice then provide an immediate need situation . For example , if you teach them a knot arrange for them to use it for real latter or if you want to teach them to be prepared arrange for something to disapear or break. I even use the same thing on my self , I'll go full survival for a weekend with a nice tent full of goodies set up, that way I have the immediate needs of survival to hone my skills and teach me and it's no more dangerous than camping since I can always retreat to my tent and goodies. Gota go to work now hope my thoughts were helpful , I think the boys are lucky to have you as a leader .