Again, once you have the individual (1v1) movement sorted out, move to a slightly more dynamic situation - the first and second defender routine. The kids get it quick. It makes sense to them and they'll bring it to the game.
I watched a junior coach the other week bring a small laptop to training and show the kids what was wanted for a single activity. Not overdone. Clever coach. A quick couple of minutes to display the skill and on to the pitch. Back off to let the kids look at the skill again, comment on what they got right and wrong and back on to the pitch. Worked a treat.The kids are good visual learners and its a medium they are all very familiar with. Not necessary, but very helpful.