Book-teaching

[…] and they are offered to the Student, in the hope that he may be encouraged to fill in the details from actual observation, and thereby cultivate a habit of self-reliance, instead of depending too much on book-teaching in his early studies.

A teacher who fails in one will fail in the other for the same reasons,—through lack of knowledge of where science impinges upon the child's interests and experience,—and book-teaching rather than teaching with the object itself.