then be disciplined enough to do it and not just run and chase. A thing I used to do was try to trick them with misdirection then yell "freeze!" to get them to stop in place. Then we could talk about what happened and why we "do our own job".
A lot of people are going to say that you let everyone run the ball or play linebacker or whatever. The problem with that is that every kid doesn't want to do that, or doesn't know that they don't want to do that...yet. The worst thing to do is make a get kid get embarrassed. So why give the ball to a kid in the game that is going to embarrass themselves? That's crazy. So explain to them the importance of every position, and how any position can be fun.
But in practice? Oh yeah, let them run it a little.
As far as offense, make it easy. Run a couple formations that build upon themselves. So you could do a shotgun where they do the same thing on every play, for example. But when you give them the play, that tells the kids who gets the ball. So you could do play one, again out of the gun, as the handoff. Two is the keeper. Three is the pass to the x. Four to the z. Stuff like that. It's easy, and the other team will never be able to figure out what you're doing, and your kids will run it to perfection.