The following is from B.B. Hofmann's 1892 book The Sloyd System of Woodworking

Primarily Sloyd is to be used as a means of formal education—formal as opposed to material. A material education seeks to impart a definite knowledge of things for their own sake. A formal education seeks chiefly to develop the innate mental powers, and selects and imparts knowledge in order to strengthen character, will-power, memory, perception—in short, all of those faculties of the mind which at birth are dormant, and which gradually and through education become to a greater or lesser degree marked characteristics of the individual.

All subjects can be used both for material and formal instruction—some more, some less. History and science give material information; and yet, if the teacher seeks to arouse the imaginative faculty, or to inspire a love and sympathy for humanity, a formal training is thereby added. The child when he studies his history lessons sees that among the first causes of a nation's welfare may" be traced the underlying principle of order. Again, as he becomes acquainted with the elements of the sciences, and as he begins to understand the workings of nature's laws, a desire to systematize and arrange things in a rational and orderly manner takes possession of his mind. Mathematics and gymnastics are of more value as formal than as material means of education, as the former develops the reasoning faculty, while the latter strengthens the body. Materialists believe in giving a knowledge of the actual things met with in life, while the formalists lay stress upon the cultivation of correct habits.

One of the interesting things you will note in this passage is the unusual use of the words "formal education" giving a meaning distinctly different from that in common use in the US. Otto Salomon referred to this concept in Swedish as Formell which was translated as "formative." This presents an interesting reminder of the various purposes of education, and presents a distinct divergence from the usual understanding that woodworking in schools was purely for vocational purposes.