They seem to me to be built upon the supposition that every child is a kind of idiot who must taught to think. Whereas if the child is left to himself, he will think more and better, if less slowly. Let him come and go freely, let him touch real things and combine his impressions for himself, instead of sitting indoors at a little round table while a sweet-voiced teacher suggest that he build a stone wall with his wooden blocks, or make a rainbow out of strips of colored paper, or plant straw trees in flower pots. Such teaching fills the mind with artificial associations that must be got rid of before the child can develop independent ideas out of actual experiences. This is not true.
Learners make learning.
The reason, I think, is that a normal adult never stops to think about problems of space and time. These are things which he has thought about as a child. In a homeschooling environment, the teacher need not be certified, but the child MUST learn. In a public school environment, the teacher MUST be certified, but the child need NOT learn. Too often we give children answers to remember rather than problems to solve.