The thing im trying to say is kids should be able to use magic (even know most kids do] buts whats wrong with it! kids might be curious but that's great because curiosity makes kids more energized for their spell for example theirs fairy spells they can use and luck spells just they need to be supervised so they dont do black magic or revenge spells or summoning demons or spirits but i might be young but im pretty sure to summon evil things.... im Epic like that (my grammar might not be very good but you get my point.)
This is well demonstrated in the three faces of the goddess in wicca, - the maiden, the mother, and the crone. All are necessary to make the complete picture. What the maiden lacks in experience, she makes up for in stamina. What the crone lacks in stamina, she makes up for in wisdom. The mother cares each way, being a figure abundance of nurturing, - the edge of stamina and the edge of wisdom. So, you see, it takes everyone to make the whole. We compliment, rather than compete. :)
I think its great for kids to learn, but just like a child has limitations under the law, they need to understand that until they reach adulthood, they should not use advanced magick. I think that 16 to 18 to is a decent age IF the person has already had at least two or three years of serious experience. There are too many dangers, and if they don't have a mentor in real life to turn to in case they get in over their heads, they should take things slowly. Children and teens tend to freak out quickly when something doesn't go the way they intended or is out of their control. It's necessary to have a level head and know what to do to resolve any possible situation that can arise from a ritual or spell. Most experienced magickal practioners plan trusted safety measures in advance. There is much to be learned, enjoyed and experienced in magick. There is no need to rush into anything.
Just as in life people mature differently. Children go through puberty at diffrent times and diffrent rates. Same goes with practicing magick. To set a standard minimum age to do certian spells would be simply ignorant. Rather it be based on experiance and natural talent. Of course those who have more natural talent than others would require less experiance.
But despite this you never really know quite how experianced you are and if you could handle advanced forms of magick. So it is better off to be safe and just wait until prefrably highschool years with the experiance. Because a little extra practice would never hurt anyone. There is no need to rush into things and mess something up.