What transition offense would be most suitable for an U12 boys team who are in their first season at a representative level?

Coach -

A lot of what you can do hinges on their talent level.... ( that goes for every age group ) These are young kids, whatever you do keep it simple, so they can just play and not have to think too much.

I would think that there are a lot of seconday breaks out there.... but I think IF this was me, I would stick to the primary.... point guard pushing the ball, players filling the lanes and first post player going ball side blcok.

There are a lot of fundamentals to teach players of this age group. I would make sure that I covered that first.

I agree with Coach Sar. Keep it VERY simple. That way, you can spend more time on fundamentals, concepts, and defense.

Here is a very simple one from Paul Westhead:
http://www.breakthroughbasketball.com/offense/paul-westhead-fast-break-offense.html

Great. I've been doing just that and teaching the principles of 5 out motion which they are starting to understand and actually execute in the game! Thanks so much.