The building of knowledge is not obtained through increased teacher direction. Rather, there is a decrease in the amount of teaching and an increase of student projects. The projects that he emphasized was with his Lego Logo program. The students were involved in programming the computer and designing projects based on their interests. The students were involved in concrete critical thinking skills that most teachers would be interested in having in their classrooms.
School spends little time on concrete tasks because the ultimate goal is the abstract.
Rather, educators should wallow in the concreteness. Concrete thinking is not just for the young. When most adults use mathematics, they rely on the concrete form. For example for dividing recipes, most people divide the recipe with their measuring cups. They do not tend to invert the second term and multiply to find out how much flour to use.