Gatto asserts the following regarding what school does to children in Dumbing Us Down:

It confuses the students.
It presents an incoherent ensemble of information that the child needs to memorize to stay in school.

(Apart from the tests and trials, this programming is similar to the television; it fills almost all the "free" time of children. One sees and hears something, only to forget it again.)
It teaches them to accept their class affiliation.
It makes them indifferent.

It makes them emotionally dependent.
It makes them intellectually dependent.
It teaches them a kind of self-confidence that requires constant confirmation by experts (provisional self-esteem).
It makes it clear to them that they cannot hide, because they are always supervised.