Everything seems to start happening around age 10. Hermetic apprenticeships, hedge apprenticeships, mundane craft apprenticeships... the first five years of life are explained well enough, but what did children do between the ages of 5-10? The child of a craftsman, for example, did he or she help out around the shop? If so, why is that not an apprenticeship?
One can be helping out and not be a formal apprentice. If you're a farmer there are plenty of tasks that a 6-10 year old can help out with, if your parents are craftsmen I suspect it's similar. A cooper may not show his 6 year old son how to build a barrel but his son can fetch tools or tidy up. (That last one is a guess on my part, my six-year-old hasn't shown any great abilities in the "tidy up" category 
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Doesn't C&G treat this? Concerning apprenticeship and when children start out?
Not that I can recall. But my memory may delude me.
In my understaning a 5 year old child will slowly develop from "don't get between my feets" to "help their parents". Starting with quite simple tasks like operating the bellows for a blacksmith or fetching wood for the oven etc. When the child gets older it can carry out more complicated or mor exhaustive tasks.
As this is a continuous process the age of 10 is just a way to simplify the game mechanism ... imho. So if its comming to XPs I would suggest to give the child some exposure XPs to be allocated to physical abilities, crafts and some knowlege abilities
salvete
Widewitt
Your memory doesn't really delude you...concerning this in any case.
I just browsed C&G, and it mentions apprenticeship starting at age 10, and nothing really about the time before. But children age 5-10 most likely srat out with the little things, menial work in the ligher end. Peasant children might help gather or herd animals. Craftsmen's children might as was mentioned work the bellows, sweep, fetch water or materials. or help mind their younger siblings.
So childs with younger brothers and sisters will end up with an score of 1 for leadership at the age of 10 
Widewitt
I really like that idea actually.
Age of reason is seven, when children are considered by the church to be culpable morally for their actions.
Children worked a lot, where they could. Otherwise, they "played". Keep in mind what your childhood was like. Now remove any sort of proper adult supervision. And any notion of temperance in justice, or the notion that "justice" was the responsibility of someone else. And habitual violence at all levels of society.
Yep. They be scrapping. Lots of fights for boys.
In some places the death rates of children under 7 were as high as 25% (Estonian Journal of Arcehology) in the 12th century.
So in these places a 1/4 of them no doubt spent some time dying....
A
No. No "pro´s" doesnt mean absence of adults.
And with children being around parents or older siblings far more probably means less time away from "supervision" than today.
Really? Disagree.
Say WHAT??? If that was true, the lack of medical care would probably mean a doubling of mortality rates.
That or even more i would say is totally realistic. Probably some points in the social skills as well.
Because they mostly did simple things, although a gifted child might easily begin learning a trade well before 10.
And by age 10 a starting apprentice could very well already have a score of 1 or 2 in the craft/profession if they were good learners or if their parents or masters began instructing them early(probably not so uncommon, but hard to say).
lol. The stuff people think they know about the middle ages (and beyond.)
Sometime when you've got nothing to do, read one of the (now legion) books of French history dealing exclusively with the criminal archives of pre-revolutionary France.
You know all those "though" neighbourhoods in America in the 1960s and 70s? The Wild West? The UFC?
Bhuddist convents.
There was no police at the time in rural areas. The nobles had toughs which weren't much more than their gang-style enforcers.
The Renaissance Kings introduced revolutionary reforms which introduced a force specifically for the keeping of the police (well, mostly) called the chevechausse in parts of France. In the Haute Auvergne, they had almost 12 people. Enough to visit many towns as often as once a year.
Murder rates were many, many, many, many, many times what they were today. And that's just the murders we know about. Ditto assaults.
Because there was so little recourse to officials, many people took out their grudges themselves. You had to stand up for yourself because, just like in gradeschool, if you let someone push you around, you became an easy mark. How you dealt with this might be a duel, a barfight, an ambush or a vendetta. But dealt with it would be.
Consider, for example this easy to find chart with links to articles here
Its not hard to find others. This is a common topic for undergraduate history students, to shake them from their fuzzy blankets of presentism. The past was far, far more violent than the present. Same goes for "kids."