I think you are asking the wrong question. Being 10 will be two young for some participants, and some could likely handle it younger. This is really a question of making sure that your nieces are mature enough (some children may not be) and you find the right instructor.
As with most skill related activities, the arbitrary age chosen is not nearly as important as finding the right teacher.
Just my two cents.
As with most skill related activities, the arbitrary age chosen is not nearly as important as finding the right teacher.
Just my two cents.