dpurdy has some nice examples. I'd post some of mine but they are boys primarily. The reccomendations to let the child guide the shoot is a great one... it works. In terms of other examples, one good source I've noticed are advertisement for clothing. Here in the US I think that would be considered somewhere between "childrens" and "juniors". The advertizing folks seems to have mastered the balance you seek. That pre-teen age is a difficult because, like the early teen years, there is still a whole lot of variability in maturity... both physical, emotional, and intellectual.