...there is one thing she [the teacher] must never do and that is, to interfere by praising a child's work, or punishing him if it is wrong, or even by correcting his mistakes [my emphasis]. 
As soon as concentration has begun, act as if the child does not exist. 
So, what science and practical life both need must surely be accepted from the start as necessary in education. This is the possibility of "recognizing one's own mistakes." We must provide this as well as instruction and materials on which to work. the power to make progress comes in large measure from having freedom and an assured path along which to go; but to this must also be added some way of knowing if, and when, we have left the path.