I have been teaching the kids classes for the past two years. You are severely underestimating the attention span of children. They cannot be bored for a second or you will lose them completely. In my opinion one hour of technique is too much. The best way to run a class is develop games that mimic the movements you want them to make. If you are going to attempt to have them sit in one spot and focus you will be lucky if its for 15 minutes. You have to be fun and firm. It has taken me forever to create tricks to keep their attention. Mechanically some kids are way ahead of others and this usually has nothing to do with age. Take it class by class and spread the techniques out. For example, first week, just learning what half guard means, traditional and lock down. Spend 15 minutes on the lockdown, then you need to switch to fun and games for the remainder. But there are ways to make them mimic the moves within activities. Keep it simple-stupid. Next class will be, what do underhooks mean, why are they important, what does it look like, then play the hugging game. They face eachother and the first one to hug the other with both arms under the armpits wins. If you do not mask the techniques within games they will get bored and misbehave. Remember, it has little to do with the perfection of techniques and more to do with them looking up to you like a superhero. Research games, camp games, gym class games, memory games etc... then figure out how to turn those games into BJJ versions of them. Little steps at a time. Grips (Gable, S, Ball and Chain etc.), How to hold onto the back, posing in different guards (open, closed, rubber, butterfly etc.) learning how to get their knees to their ears while on their backs so they can get used to inverting for granbys, Teaching them the difference between 50% and 100%, how to be good drilling partners (don't resist, stay focused etc.), how to bridge, how to sprawl, get them used to armbarring you, taking you down with ankle picks, squeezing your neck when they are on your back and learning to let go when you tap. All of these are introductory ways to prepare the kids for the daunting experience of having them want to learn how to properly whip someone up from half guard. I have been teaching some of my students for years now and they are still not ready to do sweeps with more that 3 steps to them. Hope this helps, don't be hesitant to play instead of instruct. If they feel like you are in control of guiding them through game after game they will pay attention. But if you ask them to sit and watch you as you teach them a detail, they will challenge your patience at every chance. Good luck!