I only know a little about this subject,but I was a youth camp counselor for 8 years, 6 of them specialized in 3-6yo. I agree with the author on the '2yo is to

I only know a little about this subject,but I was a youth camp counselor for 8 years, 6 of them specialized in 3-6yo. I agree with the author on the '2yo is too young' point. Obviously it depends on the children, we are all different, but I have noticed that even some early 3yo have trouble 'socializing' (or what count as socializing at this age, before ~4-5 yo, I.e stealing from each other, fighting over the stolen objects, then learning to share.). I also agree that we don't know much, but: I would 100% advise every parent to attend least send their children to a youth camp during summer around 5-6yo (4 even if you think he is early in his development). If the counselor is great, you will get back children who have sung with other for a week (once two of my charges started harmonizing by themselves, without me prompting them to, this was great), learn enough knots to impress you (especially considering the focus and dexterity of a 4yo child), and tell you stories about building homes for forest fairies. And even if the counselor isn't _that_ great (I will stop giving myself flowers someday, today's not the day though), your child will socialise for a week, probably learn interesting stuff (and probably sing too, this is like counselor 101).