There is no need for schools to teach things we all learn automatically. However, such reteaching is pervasive. One area where this is true is in the teaching of grammar. Countless numbers of school children have been taught about gerunds, the subjunctive, and how to diagram sentences. They are taught these things as knowledge to be memorized rather than as knowledge to be used. One reason for this is that they usually already know how to use such knowledge -- they speak English prior to entering school after all. Scholars may be intrigued with the problem of formalizing the structure of the English language, but the theories they construct are of no practical import to most citizens. After all, when was the last time you diagrammed a sentence? If children do not properly use the subjunctive when speaking, the right thing to do is to correct them when speaking, to teach them in the natural context, in the way they learned to speak in the first place. Having them memorize some vocabulary about grammar is worse than useless.
So when a psychologist notes that certain categories are basic to thinking this does not mean that we must rush out and teach what we have found to small children. The reason is simple--either they already know this stuff in the way that matters (they can use it)--or they will acquire it naturally as they grow up. School is not supposed to be a place where we learn vocabulary to describe what we already know how to do in the first place.
Hirsch and Schemas
Where am I in the content of the book?