Quote headhunter="headhunter"They are U9's, playing backs v forwards and having them running into each other would be just about the worst thing you could do. I'm not even sure that it would be a good idea to have the backs against the forwards at any level but at U9s it would just be terrible.'"
That was my first thought too along with the physical exercise/warming up stuff.
My brother coaches from U8 to U11, and hands up right here, its at a RU club but that makes very little difference, up to ten years old they don't tackle at all but play tag rugby instead and as you'd expect from RU they don't "play the ball" at a tag but just pass it instead.
Non contested three man (boy???) scrums are introduced at 10 years, that should be easy to replicate in RL as the pros do nothing more than lean on each other for a few seconds

, the other technical Union stuff like line outs and rucking come later, that sort of stuff is not for the U10s
THE most important thing, your top priority, should be to make their time fun - so what if they can't fling a pass out onto the wing from the centre circle, or if you find a lad that does then find that the winger can't catch - it doesn't matter if the ball goes to ground or even a little forward and you certainly should n't start to get pedantic about offsides and suchlike - just try a few little routines, run a line up and down the pitch and get them passing to each other, if you're happy that they can do that then get a game going as soon as possible, and keep it going without lots of silly breaks for explanations and penalties.
In doing so they'll enjoy their time with you, they'll learn from each other without even thinking about it (there are always one or two who's dad has been coaching them since they could walk), and they'll want to come back next week - if you spend half an hour with them sitting in a circle while you explain Stevos Momentum Rule you'll be the only one at training next week.
Above all else, and I can't believe that you've got this far without this - find out what your club intend to do with your U9s and what their child rugby policy is.
But above all else get them to enjoy it and you will too, its very rewarding.