The paper describes evolution of an approach to teaching mathematically disabled and slow learning students through a Piagetian framework. It is explained that a step-by-step procedure is used to internalize material actions into mental actions via perception and verbalization. Formulae are introduced early, and emphasis is placed on promoting generalization. The issue of the choice of the material actions most suited for the subject to be taught is discussed, and the balance concept is favored over the traditional part-whole relationship. A final comment on the principle of mathematical variability illustrates the need to help students examine relations from various points of view. (CL)